ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • American Institute of Physics (AIP)  (77,901)
  • American Association for the Advancement of Science  (74,137)
  • Annual Reviews
  • Copernicus
  • 2005-2009  (40,515)
  • 1990-1994  (70,416)
  • 1985-1989  (53,230)
  • 1980-1984  (19,310)
Collection
Keywords
Publisher
Years
Year
  • 101
    Electronic Resource
    Electronic Resource
    Millimeter-wave detection by YBaCuO step-edge microbridge Josephson junction (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3567-3571 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Millimeter-wave detection was investigated using a step-edge microbridge Josephson junction fabricated by a YBaCuO thin film for both the video detection and harmonic mixing detection. Current–voltage (I–V) characteristics, which could be described by the resistively shunted junction (RSJ) model, were obtained up to 70 K with the IcR product of 150 μV at 70 K. The responsivity and noise equivalent input power were calculated as 2400 W/V and 4.4×10−14 W/(square root of)Hz, respectively, in the video detection assuming the RSJ model approximation. Clear dependence of the intermediate frequency output on the applied dc bias voltage was observed in the harmonic mixing detection with the harmonic numbers of 5–16, reflecting the change of dynamic resistance at the constant voltage steps induced by the local oscillation signal on the I–V curve. A minimum detection power of −59.4 dB m and a conversion efficiency (η) of −49.6 dB were obtained for the harmonic number (N) of 5 at 60 K. The relationship between the η and N was expressed as η∝N−2.2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354536
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 102
    Electronic Resource
    Electronic Resource
    Blue-light electroluminescence from p-phenylene vinylene-based copolymers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3584-3586 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electroluminescence (EL) in the blue region of the spectrum with a maximum at 465 nm was observed from polymer films sandwiched between indium-tin-oxide and Al electrodes. The specially designed soluble multiblock copolymers used consisted of chromophoric units that have uniform conjugation length and are spaced with polymethylene units of various lengths. EL originates from the radiative decay of the chromophore singlet excitation created as a result of the recombination of injected charge carriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354539
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 103
    Electronic Resource
    Electronic Resource
    A new stable ferromagnetic phase in Nd-Fe-B magnets and its effect on coercivity (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3596-3598 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The microstructure and coercivity of NdxFe93−xB7 (x=16–28) sintered magnets were systematically studied. A new stable ferromagnetic phase with a composition of NdFe2Ox (x≈0.3) and a Curie temperature of 145 °C is found in the intergranular regions of the magnets, owing to the introduction of oxygen in the magnet processing. It forms at ∼650 °C and its volume fraction reaches a maximum of ∼4% in the Nd22Fe71B7 magnets. The coercivity is considerably enhanced by the appearance of this new phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354494
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 104
    Electronic Resource
    Electronic Resource
    Temporal synchronization of independently frequency tunable dual CO2 laser pulses (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3599-3601 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a new method for the simultaneous emission of two CO2 laser pulses from a single transversely excited atmospheric discharge. The transient gains of the pulsed low-pressure sections of two spatially separate hybrid cavities aligned on the discharge were temporally manipulated to allow low-jitter pulse synchronization. Independently frequency tunable dual laser pulses over arbitrarily selected rotational transitions spanning the available P and R branches of the 9 and 10 μm CO2 laser transitions were obtained, overcoming limitations on possible dual frequency combinations that restricted previous techniques. The result of numerical calculations for the hybrid laser, using a four-level rate equation model, supports the observed delay characteristics and provides a physical basis for understanding the dynamics of the synchronization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354495
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 105
    Electronic Resource
    Electronic Resource
    Photorefractive effect in a poled polymer containing the tricyanovinylcarbazole group (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3617-3619 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The photorefractive properties of a poled polymer containing the tricyanovinylcarbazole group with an alkylene spacer are investigated by four-wave mixing experiments and Mach–Zehnder type electro-optic measurements. The photorefractive effect is demonstrated in a polymer that shows both the photoconductivity and the electro-optic effect intrinsically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354501
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 106
    Electronic Resource
    Electronic Resource
    Comment on "Evaluation of the minority carrier diffusion length and edge surface-recombination velocity in GaAs p/n solar cells'' [J. Appl. Phys. 72, 2919 (1992)] (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 3620-3621 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The recent findings of Hakimzadeh, Möller, and Bailey [J. Appl. Phys. 72, 2919 (1992)] regarding the determination of minority carrier diffusion length from electron-beam-induced current data are compared to the results of an earlier study by Luke, von Roos, and Cheng [J. Appl. Phys. 57, 1978 (1985)]. The differences are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354502
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 107
    Electronic Resource
    Electronic Resource
    Speed properties of a semiconductor-discharge gap IR image converter studied with a streak camera system (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2159-2166 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Under certain experimental conditions a semiconductor-discharge gap structure can be used as detector for spatiotemporal resolved measurements on IR radiation. With a streak camera system and a semiconductor laser diode (λ=1.3 μm), we investigate experimentally the speed properties of this kind of converter. The experimental results are compared with the predictions of a simple theoretical model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354749
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 108
    Electronic Resource
    Electronic Resource
    A numerical analysis of the double periodic reflection metal grating for multiquantum well infrared photodetectors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2192-2196 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Two normalized parameters (i.e., s=λ/g and h=a/g, where g is the grating period and a is the width of metal dot) are introduced to characterize the two-dimensional (2D) double periodic reflection metal grating coupler for a multiquantum well infrared photodetector (QWIP). The "method of moments'' is used to analyze this square metal grating structure for coupling the normal incident infrared (IR) radiation into the quantum wells. The main advantage for such a grating structure is that the coupling of the normal incident IR radiation is independent of its polarization direction. Two universal graphs relating the higher-order diffracted power and diffracted angle to the normalized wavelength have been constructed for the design of 2D metal grating coupled QWIPs. By using a simple scaling rule, the coupling quantum efficiency versus wavelength over a broad IR spectrum can be obtained for the grating coupled QWIPs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354725
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 109
    Electronic Resource
    Electronic Resource
    Fission-fragment excitation of the high-pressure atomic neon laser at 703.2 and 724.5 nm (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2203-2207 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of a parametric investigation of the high-pressure fission-fragment excited atomic neon laser operating on the 703.2-nm (3p[1/2]1→3s[3/2]20) and 724.5-nm (3p[1/2]1→3s[3/2]10) transitions in He/Ne/Ar and He/Ne/Kr gas mixtures are reported. The highest measured power efficiency was 0.12% using a 1550-Torr He/Ne/Kr (17/75/8) gas mixture at a pump power of 1 kW/cm3. The power efficiency and the ratio of the 703.2- to the 724.5-nm laser output as a function of total pressure, He/Ne ratio, and percent of Ar or Kr will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354727
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 110
    Electronic Resource
    Electronic Resource
    Experimental considerations concerning the velocity measurement of the relativistic electron beam in a gyrotron by means of Thomson scattering (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2229-2236 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The feasibility of Thomson scattering to determine the beam velocity in a gyrotron has been analyzed and preliminary experiments to implement such a system on our 100 GHz quasi-optical gyrotron are reported. Although the project had to be abandoned due to technical problems, the conclusions are that for the 90° scattering arrangement discussed it should be possible to determine at least one velocity component with an acceptable signal-to-noise ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354704
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 111
    Electronic Resource
    Electronic Resource
    Output characteristics of a discharge-pumped F2 laser (157 nm) with an injection-seeded unstable resonator (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2241-2246 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To improve beam quality, an injection-seeded unstable resonator was applied to a discharge-pumped F2 laser, which is normally dominated by amplified spontaneous emission with a large beam divergence when using a normal stable cavity, due to the laser's extremely high gain (a small-signal gain-length product ∼29). The time-dependent injection-seeding efficiency was obtained for various injection timings by measuring a ratio of the output laser intensity with the same polarization as the seed laser. Correlation of the injection-seeding efficiency with the temporal evolution of the laser-beam divergence was also studied. Both the time-dependent beam divergence and the injection-seeding efficiency showed degradation at a later part of the laser pulse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354706
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 112
    Electronic Resource
    Electronic Resource
    Temperature measurements of a neon Z-pinch plasma (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2260-2267 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A neon Z-pinch plasma, appropriate for sodium/neon photopumping experiments, is studied in detail using temporally, spatially, and spectrally resolved measurements of Ne VII, Ne VIII, and Ne IX emissions. The neon is imploded with a 1 μs rise time, 150–180 kA peak current pulse. Two successive implosions are identified. The first implosion produces a 1-mm-diam plasma with an electron density of 9×1019 cm−3 and a temperature of 200 eV. The second implosion produces a larger diameter (3.5 mm), less dense (7×1018 cm−3) plasma with a temperature of 100 eV. A 70% Ne IX ground-state population at the second implosion is deduced from the measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354709
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 113
    Electronic Resource
    Electronic Resource
    Germanium-doped gallium phosphide obtained by neutron irradiation (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2287-2293 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of electrical, optical, electron spin resonance and optically detected magnetic resonance studies of thermal neutron irradiated and annealed at 800 °C n-type GaP are presented. Evidence is found to support the view that the main dopant introduced via transmutation of GaP, germanium, occupies cation sites and forms neutral donors. This confirms the possibility of neutron transmutation doping of GaP. Simultaneously, it is shown that germanium is absent at cation sites. Presence of other forms of Ge-related defects is deduced from luminescence and absorption data. Some of them are tentatively identified as VGa-GeGa acceptors leading to the self-compensation process. This observation means that the neutron transmutation as a doping method in application to GaP is not as efficient as for Si.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354712
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 114
    Electronic Resource
    Electronic Resource
    Charged particle flow in plasma-filled pinched-electron-beam diodes (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2274-2286 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Plasma-filled pinched-electron-beam diode experiments have been performed on the Gamble II (1.5 MV, 800 kA, 60 ns) pulsed power generator at Naval Research Laboratory. These plasma-filled diode (PFD) experiments show three phases of behavior: a low impedance phase followed by a phase of rapidly increasing impedance that culminates in a relatively constant vacuum impedance phase. The duration of the low impedance phase as well as the final operating impedance depends on the prefill plasma density. The charged particle flow in the PFD is studied with one-dimensional (1-D) and two-dimensional (2-D) simulation models. These simulation models show the formation of growing sheaths at both electrodes during the low impedance phase. The end of the low impedance phase in the simulations coincides with the two sheaths meeting in the center of the anode-cathode (A-K) gap. Based on these observations, an analytic model was developed that treats the low impedance phase as symmetric bipolar sheaths. The analytical model adequately predicts the duration of the low impedance phase predicted by the 1-D simulation model. Differences between the bipolar model and the experiments or 2-D simulations can be explained in terms of magnetized sheaths which enhance the ion current over the bipolar level and cause the sheath to grow faster than the bipolar model. During the rapidly increasing impedance phase, the simulations show that the cathode sheath quickly expands to completely fill the A-K gap. At this time, charged particle flow in the simulation models are consistent with the vacuum gap spacing. Experimentally, the higher density, longer conduction time, PFD shots exhibited a significantly lower final impedances than predicted by 2-D simulations. This difference is probably caused by expanding electrode surface plasmas produced by the interaction of the plasma source with one or both electrode surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354711
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 115
    Electronic Resource
    Electronic Resource
    Raman scattering study on the effects of Ga ion implantation and subsequent thermal annealing for AlSb grown by molecular-beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2300-2305 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Radiation damage and its recovery process of molecular-beam epitaxy grown AlSb implanted with Ga ions is studied using Raman scattering for Ga ion fluences ranging from 1×1013 to 5×1014 cm−2 and for annealing temperatures ranging from 300 to 600 °C. With increasing fluences the AlSb longitudinal optical (LO) phonon mode shifts to lower frequency and exhibits an asymmetric broadening. Recovery of radiation damages in the ion implanted AlSb is observed after annealing at as low as 300 °C. On the other hand, after annealing at above 500 °C, disordering of the crystalline structure due to the outdiffusion of Sb is observed. The damage states and the recovering behaviors are quantitatively estimated using the spatial correlation model on the LO mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354714
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 116
    Electronic Resource
    Electronic Resource
    Enhancement of magnetic moment of iron atoms in the Fe/Au nanomultilayers (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1929-1932 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Fe/Au multilayers were prepared by alternative vapor deposition. The periodicity, thickness, chemical composition, microstructure, and the magnetic moment of the films were determined and measured by various methods. The magnetic moment per Fe atom in Fe/Au multilayers was considerably enhanced when the Fe layer thickness was thinner than 8 nm and it was up to 2.59 μB, i.e., about 1.2 times of that of bulk Fe, at an Fe layer thickness of 4.5 nm. The experimental results also revealed that as the thickness of the Fe layer decreased, there was an increasing tendency towards perpendicular magnetization in the Fe/Au multilayers. The possible mechanism responsible for the modification of magnetic properties is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355326
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 117
    Electronic Resource
    Electronic Resource
    Observation of nuclear diffraction from multilayers with a Fe/57Fe superstructure (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1933-1937 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nuclear diffraction from a 57Fe5B4C/Fe5B4C multilayer has been observed. The reflectivity was measured by Mössbauer spectroscopy in grazing incidence geometry. A pure nuclear Bragg peak showed up at the expected position in the rocking curve. The energy dependence of the reflectivity was measured at different angles near the Bragg peak. The measurements are in good agreement with the theory. The use of nuclear resonant multilayers as monochromators for synchrotron radiation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354776
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 118
    Electronic Resource
    Electronic Resource
    Contributions to the dielectric constant of the system BaLn2Ti4O12 from packing fraction and nephelauxetic ratio (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1968-1971 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An attempt has been made to identify the optimum parameters for good dielectric resonator materials. The dependence of dielectric constant of the system BaLn2Ti4O12 (Ln=La, Pr, Nd, Sm) on packing fraction and nephelauxetic ratio is discussed. The reported dielectric data for this system were treated using the multiregression method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354755
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 119
    Electronic Resource
    Electronic Resource
    Depth-resolved measurement of lattice relaxation in Ga1−xInxAs/GaAs strained layer superlattices by means of grazing-incidence x-ray diffraction (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2381-2387 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The state of relaxation in two different superlattices (SLs) of a system with large lattice mismatch, Ga0.8In0.2As/GaAs grown on GaAs [001] by molecular beam epitaxy, has been investigated by surface-sensitive grazing-incidence diffraction (GID). The SL is squeezed between the substrate and a thick GaAs top layer. The thickness of individual GaInAs layers ta (active layer) is the same in both samples, while the GaAs barrier thickness tb is different. We have studied the influence of the thickness ratio tb/ta on the state of relaxation for different distances from the sample surface. We find that for thick barriers the whole SL remains coherently strained and for the thinner barrier thickness the SL is partially relaxed against the the GaAs top layer. The GID technique was applied for the first time to obtain depth resolution of the lateral lattice parameter in a SL. It is demonstrated to be especially well suited for SL systems with a small difference of the average electron density between the sublayers. The scattering contrast is improved by measuring the intensity as a function of the exit angle ("rod scans'') from the "weak'' (200) Bragg reflection. Comparing computer simulations with the measured variation of the scattering contrast between GaAs and GaInAs layers obtained from different "information depths'' and at different angular positions of the in-plane rocking curves, the state of relaxation can quantitatively be evaluated. On the basis of these results we propose two models for the partial relaxation of the SL into the state of strain-reduced domains. We believe that the partial relaxation is due to the elastic field interaction between the GaInAs layers accross the GaAs barriers, if tb is small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354724
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 120
    Electronic Resource
    Electronic Resource
    Measurement of interface strength by the modified laser spallation technique. I. Experiment and simulation of the spallation process (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2388-2396 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Part I of this paper presents the modified laser spallation technique for measuring the tensile strength of planar interfaces, using a Doppler displacement interferometer. In this technique, a laser-produced compressive stress pulse in the substrate, reflecting from the coating's free surface pulls the interface in tension and leads to its failure if the tensile amplitude is high enough. The current technique is an improvement over the previous one, since the interface stress is determined directly by recording the coating or substrate free-surface velocities using a laser displacement interferometer. The recorded surface velocity is related to the interface stress via an elastic wave equation simulation. The process of coating spallation is investigated, and the effect of the stress pulse profile and the coating and substrate characteristics on the interface tensile stress is studied using the simulation. Several interface stress charts are given for wider applicability of the modified technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354698
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 121
    Electronic Resource
    Electronic Resource
    Measurement of intrinsic stresses during growth of aluminum nitride thin films by reactive sputter deposition (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2411-2414 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Real-time measurements of intrinsic stresses during growth of polycrystalline and epitaxial aluminum nitride (AlN) thin films on Si(111) are reported. Our room-temperature measurements on polycrystalline films corroborate previous post-growth measurements. Our high-temperature measurements provide evidence of large intrinsic stresses during epitaxial growth of AlN on Si(111) and insignificant stress relaxation during growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354701
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 122
    Electronic Resource
    Electronic Resource
    The 900 °C upper yield stress of Czochralski silicon single crystals with carbon concentrations of 4.0×1014 and 3.5×1015 cm−3 (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2420-2424 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to investigate the influence of carbon on the high-temperature strength of Czochralski silicon single crystals, we measured the 900 °C upper yield stress of crystals containing carbon at concentrations of 4.0×1014 cm−3 ("low C'') and 3.5×1015 cm−3 ("standard C''). Prior to testing, all crystals were heat treated for 20 h at 700 °C. They were then annealed at 1000 °C for periods between 1.5–7 h. During the longest anneal, the interstitial oxygen content fell from 2.0×1018 to 1.0×1018 cm−3 in low C crystals and from 1.9×1018 to 7×1017 cm−3 in "standard C'' crystals. The 900 °C upper yield stress of 7 h annealed low C crystals is 13 MPa, which is 30–40% higher than that measured in standard C crystals. The precipitate density, measured optically, is 4×105 cm−2 in low C samples and 9×105 cm−2 in standard C crystals. In all cases, the precipitates punched out dislocations. A model that assumes that the higher interstitial oxygen content retained by the low C crystals results in higher locking stresses for glide dislocations can quantitatively account for these observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354677
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 123
    Electronic Resource
    Electronic Resource
    Shock-induced mechanisms of phase transformation from rhombohedral BN to cubic BN (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2440-2444 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Rhombohedral forms of layered boron nitride (r-BN) as mixtures with copper powders were shock compressed and quenched from pressures in the range 8–50 GPa. Recovered specimens were investigated by x-ray diffraction and electron microscopy. The graphite-like BN (h-BN) and turbostratic BN (t-BN) phases are observed in the pressure range 8–22 GPa and wurtzite-type BN (w-BN) in the range 17–39 GPa. The zincblende-type BN (c-BN) phase is identified from specimens subjected to high shock temperatures and consists of very fine grains mostly less than 10 nm. The mechanism of phase transformation of r-BN to c-BN is proposed to occur through two paths: (i) direct conversion by relatively strong shocks and (ii) indirect, kinetically controlled conversion via intermediate phases by shock loadings generating relatively weak pressures (〈50 GPa). The possible intermediate phases are h-BN, t-BN, and w-BN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354680
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 124
    Electronic Resource
    Electronic Resource
    Al–Ga interdiffusion, carbon acceptor diffusion, and hole reduction in carbon-doped Al0.4Ga0.6As/GaAs superlattices: The As4 pressure effect (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2450-2460 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al–Ga interdiffusion, carbon acceptor diffusion, and hole reduction were studied in carbon doped Al0.4Ga0.6As/GaAs superlattices (SL) annealed under different ambient As4 pressure conditions in the temperature range of 825 °C–960 °C. The SL were doped with carbon to an initial acceptor concentration of ∼2.9×1019 cm−3. Al–Ga interdiffusion was found to be most prominent under Ga-rich annealing ambient conditions, with interdiffusivity values, DAl–Ga, turned out to be about two orders of magnitude smaller than those predicted by the Fermi-level effect model. Under As-rich ambient conditions, the DAl–Ga values are in approximate agreement with those predicted by the Fermi-level effect model. The hole concentrations in the SL decreased significantly after annealing under As-rich and As-poor ambient conditions, while those after annealing in the Ga-rich ambient were almost totally intact. By analyzing the measured hole concentration profiles, it has been found that both carbon acceptor diffusion and reduction have occurred during annealing. Both the carbon acceptor diffusivity data and the carbon acceptor reduction coefficient data are characterized approximately by a dependence on As4 pressure values to the one-quarter power. These As4 pressure dependencies indicate that carbon diffuses via the interstitialcy or interstitial–substitutional mechanism, while hole reduction is governed by a carbon acceptor precipitation mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354682
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 125
    Electronic Resource
    Electronic Resource
    Brillouin scattering by localized acoustic modes in silicon-oxynitride–fused-silica optical waveguides (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2475-2480 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Brillouin scattering connecting guided optical modes is used to study the acoustic waves in a silicon-oxynitride–fused-silica double layer deposited onto a Si substrate. The frequencies of the acoustic modes as derived from the acoustic wave equation are found to reproduce those of the experiment. The scattering intensities are in agreement with a calculation based on the coupled-waveguide-mode formalism with due account of the elasto-optic effect and the corrugation of the surface and silicon-oxynitride–silica interface. Finally, the sound velocities and Pockels coefficients of the silicon-oxynitride layer are determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354685
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 126
    Electronic Resource
    Electronic Resource
    Surface segregation effects of In in GaAs (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2481-2485 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence (PL), secondary-ion mass spectroscopy (SIMS), and cross-sectional transmission electron microscopy (TEM) measurements have been performed to assess surface segregation of In in GaAs during molecular-beam epitaxial growth of InAs monolayers between GaAs layers. The InAs growth temperature at which In segregation is detectable depends on the characterization technique used; using PL it is above 420 °C, but from TEM and SIMS it is 420 and 340 °C, respectively. These results highlight the need for complementary information to provide a better understanding of the segregation phenomenon. SIMS data show that the total amount of In segregating and the extent of its distribution both increase with InAs deposition temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354686
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 127
    Electronic Resource
    Electronic Resource
    X-ray diffraction characterization of ternary artificial superlattices (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2501-2506 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of alternating Au, Ag, and Cu wedge-shaped metal layers were made by magnetron sputtering in order to develop a method for investigation of a multicomponent systems. X-ray-diffraction patterns of all as-deposited samples revealed satellites in the vicinity of (111) reflections, evidence of composition-modulated artificial superlattice formation. The experimental spectra are well explained by the kinematical diffraction theory for imperfect superlattices. Computer simulations have demonstrated extremely high sensitivity to the fluctuations ΔH/H of the superlattice period H. As a result, a rapid and simple method of ΔH/H determination is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354689
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 128
    Electronic Resource
    Electronic Resource
    Bulk and interface stresses in silver-nickel multilayered thin films (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2517-2523 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Stresses were measured in 〈111〉-textured Ag/Ni multilayered thin films from the substrate curvature and from lattice parameter measurements by x-ray diffraction. The difference between the total multilayer film stress and the layer deposition stresses can be attributed to a tensile interface stress of −2.27±0.67 J/m2. Interfacial phase formation is unlikely in this system as indicated by the exceptionally low mutual solubilities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354692
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 129
    Electronic Resource
    Electronic Resource
    Critical epitaxial thicknesses for low-temperature (20–100 °C) Ge(001)2×1 growth by molecular-beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2512-2516 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth of Ge(001) by molecular-beam epitaxy at temperatures Ts between 20 and 100 °C, and deposition rates of 0.5 and 1 A(ring) s−1, was investigated using a combination of in situ reflection high-energy electron diffraction and post-deposition cross-sectional transmission electron microscopy. All films consisted of three zones beginning with a defect-free epitaxial layer of thickness t1 in which ln(t1)∝(1/Ts). The second zone was a narrower intermediate layer containing {111} stacking faults and microtwins, while the third zone was amorphous. An atomistic growth model is proposed to explain the observed morphological breakdown during low-temperature growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354691
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 130
    Electronic Resource
    Electronic Resource
    Theoretical investigation of different formulations of the electron-plasmon interaction under transient conditions (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2550-2556 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a comparison of two different methods of including the electron-electron long-range interaction on the dynamics of hot electrons in degenerate GaAs under transient conditions in two different hot electron transistor structures of 60- and 120-nm base widths, respectively. The first approach is quantum mechanically based while the second follows a semiclassical prescription. The calculated energy spectrum, velocity distribution, and percentage of injected carriers collected in the hot electron transistors are determined under three different conditions: the inclusion of the plasmon interaction through the quantum-mechanical formulation, the inclusion of the plasmon interaction through the semiclassical technique, and with no plasmon interaction. The calculated energy spectrums within the two plasmon models are qualitatively similar. They differ only by the extent to which the peaks are broadened and the absolute ratio of collected to injected carriers. Because of the very different energy relaxation within the plasmon models, the ratio of collected to injected electrons is predicted to be far smaller using the quantum-mechanical model than the semiclassical model. Subsequently, knowledge of the absolute ratio of the collected to injected carriers in a hot electron transistor would give some indication of the appropriateness of each model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354696
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 131
    Electronic Resource
    Electronic Resource
    Real-time spectroellipsometry investigation of the interaction of silane with a Pd thin film: Formation of palladium silicides (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2535-2542 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the application of spectroscopic phase modulated ellipsometry to the study of both ultrafast and slow processes of the interaction of silane (SiH4) with thin films of palladium. Changes of the optical properties of thin films exposed to different SiH4 fluxes are monitored by in situ single wavelength ellipsometry in the case of high fluxes which lead to ultrafast processes and by in situ spectroscopic ellipsometry at low fluxes and slow kinetics. The study of the interaction of SiH4 with Pd at 250 °C reveals the complicated character of the process which depends on the flux of silane and leads to the formation of palladium disilicide, palladium hydrides, and an intrinsic porosity. A qualitative model of the process is proposed. The initial stage of the reaction at high fluxes of SiH4 is dominated by a grain boundary diffusion of SiH4 inside the Pd film, followed by the catalytic decomposition of SiH4 and a strong process of an intrinsic formation of porosity. This fast process (duration of 10 ms) proceeds through the formation of a metastable Pd-rich phase. The appearance of the intrinsic porosity enhances the diffusion of SiH4 inside the Pd film, which results in a drastic acceleration of the silicide formation. At low SiH4 fluxes the characteristic time of the reaction increases up to some tens of minutes and proceeds through the formation of both silicide and palladium hydride.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354694
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 132
    Electronic Resource
    Electronic Resource
    Properties of hydrogenated amorphous silicon prepared by alternatively repeating chemical-vapor deposition from disilane and hydrogen plasma treatment (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2543-2549 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental studies have been carried out to characterize hydrogenated amorphous silicon prepared by alternatively repeating chemical-vapor deposition (CVD) from disilane and hydrogen plasma (HP) treatment (referred to as HP treated CVD a-Si:H). It has been found that hydrogen plasma treatment induces structural relaxation of Si network in addition to the passivation of Si dangling bonds. Two types of defect states with different Gaussian energy distribution exist in this material, and this type of distribution has been found to be common in undoped a-Si:H prepared by a variety of methods. High film quality, i.e., a low defect density (〈1016 cm−3) and a fairly long ambipolar diffusion length (0.12 μm), and significant reduction of light-induced changes have been simultaneously achieved in HP treated CVD a-Si:H. Steady state transport of electrons and holes under illumination are controlled by the states other than neutral Si dangling bond state (D0). The behavior of these states with long exposure to light is different from that of D0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354695
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 133
    Electronic Resource
    Electronic Resource
    Enhanced luminescence due to impact ionization in photodiodes (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2565-2571 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple mechanism explaining the enhanced luminescence of p-i-n structures and reach-though avalanche photodiodes approaching reverse-bias breakdown is proposed. The model presented predicts enhanced photon emission based on calculations of the spatial dependence of the impact ionization events. Experimentally, an enhancement of a factor of 100 in the optical efficiency is observed in p-i-n silicon photodiodes when biased in the gain regime. A series of measurements made on commercially available photodiodes are presented. Theoretical predictions are compared with the experimental photonic output versus internal electric field and current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354702
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 134
    Electronic Resource
    Electronic Resource
    The enhanced Stark effects of coupled quantum wells and their application to tunable IR photodetectors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2598-2604 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A tunable asymmetric coupled quantum well far-infrared photodetector is proposed in this paper. The basic asymmetric coupled quantum wells are composed of two quantum wells separated by a thin barrier. In this way, the electron in each well interacts strongly with other electrons to achieve a large Stark tuning effect. The eigenenergies and the wave functions of the quantum-well structures are solved by the self-consistent method, and the effect of the exchange interaction on the ground-state subband has also been taken into account. The absorption coefficient is evaluated by the density-of-states formalism. Based on theoretical calculations, tuning ranges from 8.2 to 11.3 μm and 7.8 to 10.5 μm are predicted for the proposed asymmetric coupled-quantum-well structure and high-low coupled-quantum-well structure, respectively. This tuning capability is achieved by varying the applied electric field in the 20–90-kV/cm range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355293
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 135
    Electronic Resource
    Electronic Resource
    Optimization of charge transfer to the active channel in δ-doped heterostructures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2613-2618 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An accurate theoretical model based on the two-band effective-mass-approximation that includes nonparabolic, strain, finite temperature, many-body, and deep donor (DX) center effects is used to investigate the electronic properties of δ-modulation-doped semiconductor heterostructures with the aim of optimizing the active channel density. Inclusion of the DX centers in the model leads to the saturation of the electronic density with increasing δ-doping concentration for both structures doped on one side and structures doped on both sides of the channel. The saturation value in the latter case is almost twice as high as in the former. The self-consistent calculations show that by using a superlattices of superlattices configuration with an appropriately chosen superlattice barrier one can achieve a 50% increase in the maximum charge transfer compared to conventional heterostructures of similar design, without increasing impurity scattering in the channel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354651
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 136
    Electronic Resource
    Electronic Resource
    Submillimeter wave low-temperature admittance of n-GaAs and n-InP diode structures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2633-2637 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical simulation results for n+nn+ GaAs and InP diode structures in the 1–5 THz frequency range are presented. Cryogenic temperatures from 4 through about 77 K as well as some cases above liquid-nitrogen temperature are examined to obtain the two-terminal admittance. Earlier work has suggested possible negative conductivity at or below 4.2 K, but nothing consistent above 77 K. Implications of the Monte Carlo data for generation of submillimeter waves at intermediate lattice temperatures between 4 and 60 K are discussed for GaAs. Furthermore, numerical results are obtained at elevated lattice temperatures (200 and 300 K) to form a more complete view of transport in InP. The GaAs and InP results strongly suggest negative conductance behavior will be found below 20 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354654
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 137
    Electronic Resource
    Electronic Resource
    The nature of the hole traps in reoxidized nitrided oxide gate dielectrics (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2665-2668 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: To find out the nature of hole traps in reoxidized nitrided oxide (RNO), a series of field and thermal detrapping experiments were performed following irradiation. It has been found that not only are the hole traps in RNO located near the gate-SiO2 interface instead of near the Si-SiO2 interface as in conventional dry oxides, but that the energy distribution of these traps is also quite different from that in conventional oxides. This indicates that the origin of the traps in RNO is different from that normally found in conventional oxides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354658
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 138
    Electronic Resource
    Electronic Resource
    Dynamic properties of a superconducting quantum interference device containing arrays of Josephson junctions (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2674-2680 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dynamic properties of a superconducting quantum interference device (SQUID) containing arrays of Josephson junctions in a superconducting loop, and in particular the case of a four-junction SQUID, is analyzed theoretically via computer simulations. It is shown that phase locking of Josephson junctions determines the dynamic behavior of the SQUID. In the case of a stable phase-lock state hysteretic I-V curves as well as unusual voltage-flux dependencies appear. The influence of a small spread in the Josephson junction parameters upon the stability of the phase-lock state is investigated in parameter space.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354660
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 139
    Electronic Resource
    Electronic Resource
    Magnetization reversal processes in Co-Re antiferromagnetically coupled multilayers: A magneto-optic and Monte Carlo study (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2692-2700 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A study of magnetization reversal processes in sputtered antiferromagnetically coupled (CotCoRe5 A(ring))×n multilayers, with n=2,3,5 is reported. The two components of the magnetization, parallel and perpendicular to the applied field are analyzed using a suitable transverse Kerr effect differential magneto-optical setup. At the remanent state, and for n=3, and 5, we obtain a magnetization of 1/3 and 1/5 of the saturation magnetization, respectively. This means that the magnetization in each layer is aligned parallel or antiparallel to the applied field direction. The observed perpendicular magnetization component is as expected, much smaller than the parallel magnetization component over the entire length of the hysteresis cycle. A Monte Carlo simulation was used to study the spin configurations in the individual layers as well as the type of magnetization hysteresis cycles. We find that the introduction of a small uniaxial anisotropy is needed to explain the observed multiloop structure in the n=3 multilayers. Within our model, spin-canting may occur within the ferromagnetic layers leading to particular remanent-state spin configurations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354663
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 140
    Electronic Resource
    Electronic Resource
    High-field effective linewidth and eddy current losses in moderate conductivity single-crystal M-type barium hexagonal ferrite disks at 10–60 GHz (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2705-2718 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The losses associated with the high-field tail region of the ferromagnetic resonance (FMR) absorption curve were investigated at 10, 19, 35, and 60 GHz for 0.10–1.75-mm-thick c-plane circular disks of flux-grown single-crystal M-type barium ferrite materials. A conventional high-field effective linewidth analysis of the data yielded an effective linewidth which increased with the square of the disk thickness and linearly with frequency, dependencies which indicate a predominant eddy current loss process. Based on these results, an eddy current loss analysis of the tail region was done, based on the insulator FMR response and eddy current losses driven by the FMR response. This analysis leads to a new noninvasive technique for the determination of the microwave conductivity in moderate conductivity ferrites. One obtains the conductivity from an appropriate analysis of the FMR absorption tail in the same way that analysis of the magnetic loss tail yields a high-field effective linewidth. Based on this technique, the microwave conductivity of these flux-grown barium ferrite single-crystal materials was determined as a function of frequency and found to increase linearly from 0.033±0.004 Ω−1 cm−1 at 10 GHz to 0.10±0.02 Ω−1 cm−1 at 60 GHz. These results are consistent with a measured dc conductivity of 0.03–0.05 Ω−1 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354665
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 141
    Electronic Resource
    Electronic Resource
    Non-steady-state photoelectromotive force in semiconductor crystals with high light absorption (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2736-2741 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of a high light absorption on the photoelectromotive force excited by moving interference fringes in photoconductive crystals is considered. It is shown that due to a deep penetration of the electric field pattern into the sample volume, the absolute magnitude of the output signal and its dependence on the spatial frequency of the grating may practically be the same as for low absorption. This conclusion is confirmed experimentally for semi-insulating GaAs:Cr for λ=633, 840–900, and 1064 nm. This means, in particular, that films or thin specimens of photoconductive materials can be used for fabrication of adaptive detectors of phase-modulated optical signals with the same efficiency as bulk specimens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354669
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 142
    Electronic Resource
    Electronic Resource
    Quantitative characterization of modulation-doped strained quantum wells through line-shape analysis of room-temperature photoluminescence spectra (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2760-2767 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Room-temperature photoluminescence (PL) has been used to characterize modulation-doped AlGaAs/InGaAs/superlattice strained layer quantum wells. A phenomenological line-shape model has been developed which can be fitted to PL spectra in order to obtain key parameters such as the subband energies, Fermi energy, and transition amplitudes. Quantum well sheet densities calculated from fits to the PL spectra (taken at both room temperature and 77 K) have been compared to sheet densities obtained from low-temperature Hall measurements. It has also been shown how variations in quantum well composition, width, and symmetry can be characterized by shifts in values of the relevant fitting parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355322
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 143
    Electronic Resource
    Electronic Resource
    The Ag/As2S3 photodoping mechanism: Photon absorption (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2768-2770 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The sensitivity of the Ag-photodoping process has been measured as a function of photon energy between 1.9 and 6.4 eV. The sensitivity increases with increasing photon energy except at 3.8 eV (325 nm) where Ag exhibits an anomalous window. At this energy there is an abrupt and large decrease of sensitivity. In a second measurement, the transmission as a function of wavelength between 200 and 900 nm of a 2000-A(ring)-thick film of As2S3 doped with an imaging dose of Ag and a second sample doped with a larger than imaging dose are compared with an undoped sample. Band-gap shrinkage is different for the two doses. Both measurements suggest that under certain conditions, photon absorption in the Ag-photodoping process occurs in the Ag.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354646
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 144
    Electronic Resource
    Electronic Resource
    Exciton luminescence in Si1−xGex/Si heterostructures grown by molecular beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2790-2805 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Coherent Si1−xGex alloys and multilayers synthesized by molecular beam epitaxy (MBE) on Si(100) substrates have been characterized by low-temperature photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM). Phonon-resolved transitions originating from excitons bound to shallow impurities were observed in addition to a broad band of intense luminescence. The broad PL band was predominant when the alloy layer thickness was greater than 40–100 A(ring), depending on x and the strain energy density. The strength of the broad PL band was correlated with the areal density (up to ∼109 cm−2) of strain perturbations (local lattice dilation ∼15 A(ring) in diameter) observed in plan-view TEM. Thinner alloy layers exhibited phonon-resolved PL spectra, similar to bulk material, but shifted in energy due to strain and hole quantum confinement. Photoluminescence excitation spectroscopy, external quantum efficiency, time-resolved PL decay, together with the power and temperature dependence of luminescence intensity, have been used to characterize Si1−xGex/Si heterostructures exhibiting both types of PL spectra. The role of MBE growth parameters in determining optical properties was investigated by changing the quantum well thickness and growth temperature. The transition from phonon-resolved, near-band-gap luminescence in thin layers to the broad PL band typical of thick layers is discussed in terms of a strain energy balance model which predicts a "transition thickness'' which decreases with increase in x.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354628
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 145
    Electronic Resource
    Electronic Resource
    Polyimide ablation using intense laser beams (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2830-2833 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The ablation of polyimide by intense UV laser beams is modeled with a photothermal process that considers the shielding of the laser beam by the decomposed polymer. The heating of the decomposed material may drive the polymer degradation process for fluences above several J/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354634
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 146
    Electronic Resource
    Electronic Resource
    Effect of graphitic carbon films on diamond nucleation by microwave-plasma-enhanced chemical-vapor deposition (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2841-2849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond nucleation on very smooth (100) silicon substrates coated with thin films of a colloidal graphite suspension was investigated with a microwave-plasma-enhanced chemical-vapor-deposition system. Nucleation densities of the order of 106 cm−2 were obtained by coating the substrates with carbon films of thicknesses less than 1 μm. However, very low nucleation densities were obtained with carbon film thicknesses greater than 1 μm. The effect of the carbon film thickness on diamond nucleation was examined by measuring the etching rate of carbon films exposed to a hydrogen plasma and was further interpreted on the basis of scanning electron microscopy and Raman spectroscopy results. Etching of the original carbon may lead to the formation of a thin residual carbon film when the initial film thickness is less than a critical value. Results demonstrated that the high nucleation densities of good quality cubo-octahedral diamond crystals obtained with relatively thin carbon films were primarily due to the formation of a porous ultrathin residual carbon film. The critical initial film thickness was a function of the plasma etching and deposition rates of carbon which, in turn, affected the effective local carbon concentration. Thick carbon films yielded insignificant nucleation densities and poor quality diamond because of the high local carbon content resulting from the partial etching of carbon and the increased carbon concentration in the plasma. The local carbon concentration and the residual carbon film are the proposed principal factors for the obtained high diamond nucleation densities on unscratched silicon substrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354636
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 147
    Electronic Resource
    Electronic Resource
    Doping effect of buckminsterfullerene in poly(2,5-dialkoxy-p-phenylene vinylene) (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2860-2865 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoluminescence has been markedly quenched and photoconductivity has been enhanced by more than one order of magnitude upon introduction of several mol% of buckminsterfullerene (C60) to poly(2,5-dialkoxy-p-phenylene vinylene) (RO-PPV), especially at excitations about 2.2 eV, corresponding to the band gap energy of RO-PPV and also in bands at 1.8 and 3.5 eV, which correspond to optical excitation of C60 molecules, suggesting that photo-induced charge transfer occurs between RO-PPV and C60. On the other hand, absorption spectrum and electrical conductivity of RO-PPV have been scarcely influenced by doping of small amount of C60, suggesting that the ground state charge transfer between C60 and RO-PPV is not effective, contrary to the case of poly(3-hexylthiophene). These results are discussed by taking relative electronic energy states of RO-PPV and C60 into consideration. The photo-excited exciton-polaron (Ex-P) in RO-PPV is interpreted to migrate along about 100 monomer units along a polymer main chain in its lifetime and dissociates when encountered with C60. These unique doping characteristics of C60 in RO-PPV are not dependent on the alkyl chain length, contrary to the case of poly(3-alkylthiophene).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354639
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 148
    Electronic Resource
    Electronic Resource
    Plasma chemistry of He/O2/SiH4 and He/N2O/SiH4 mixtures for remote plasma-activated chemical-vapor deposition of silicon dioxide (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6538-6553 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Remote plasma-activated chemical-vapor deposition (RPACVD) provides a means to deposit thin dielectric films with low ion bombardment and while having high selectivity in generating precursors. In RPACVD of SiO2, gas mixtures of He/O2 or He/N2O are passed through a plasma, producing radicals and excited states that are mixed with silane downstream. Excited states produced in the plasma and precursor species produced by these reactions then flow to the substrate. Although high-quality SiO2 films can be produced by RPACVD, the gas-phase deposition precursors have not been identified. A two-dimensional plasma chemistry model is described, and results from that model are used in a discussion of possible gas-phase precursors for SiO2 deposition. In particular, the formation and transport of silanols (SiH2O and SiH3O) are examined as a function of gas mixture, power deposition, and geometry. It is found that the fluxes of SiH2O, SiH3O, and SiH3 are sufficient to account for the observed deposition rates; while systematic dependencies of the fluxes of HSiO and SiO discount them as being deposition precursors. He/N2O/SiH4 mixtures differ from He/O2/SiH4 mixtures by providing larger fluxes of SiH3 to the substrate, while the fluxes of SiH2O, SiH3O, and O2(1Δ) are significantly less.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355115
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 149
    Electronic Resource
    Electronic Resource
    An ordered Ga2Te3 phase in the ZnTe/GaSb interface (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6566-6570 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A Ga2Te3 interfacial phase has been observed in a ZnTe/(001)GaSb heterostructure by high resolution electron microscopy under special imaging conditions. This phase exists in domains 5–10 nm in size on the ZnTe side of, and usually 2–4 nm away from, the interface. A structural model has been proposed for this phase that is derived from the sphalerite cell with cation sites occupied either fully (occupancy 1) or partially (occupancy 5/9) by Ga atoms. The fully occupied Ga sites form a regular array of uninterrupted chains along the [110] direction of the sphalerite unit cell. The partially occupied Ga sites can also be considered as forming chains containing both Ga atoms and vacancies along the [110] direction. Within these chains vacancies are highly mobile, resulting in an average Ga occupancy of 5/9. The unit cell of Ga2Te3 is orthorhombic with the space group Amm2. The lattice parameters of the unit cell have been derived from electron diffraction data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355118
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 150
    Electronic Resource
    Electronic Resource
    The gettering efficiency of a direct bonded interface (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6576-6579 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In these studies the gettering efficiency of copper at a direct bonded interface is compared to the gettering efficiency of a bulk defect zone formed during a one step and three step annealing process of Czochralski silicon wafers. The gettering efficiency of a bulk defect zone is considerably higher than that of the interface. Thus intrinsic gettering is expected to be effective in gettering direct bonded p-n junctions. Without any intrinsic gettering zone, copper silicide readily precipitates at the bonded interface, forming complex star-shaped colonies. Their morphology changes into single colonies in {110} planes if the wafer pairs are prestressed during contacting at room temperature. In this case the gettering efficiency of the bonded interface increases in comparison to the bulk defect zone. Prestressing experiments have shown that the denuded zone width in tensile stressed regions of a wafer increases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355095
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 151
    Electronic Resource
    Electronic Resource
    Current conduction in an implant isolated GaAs/AlGaAs heterostructure (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6571-6575 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the current-voltage characteristics of an oxygen implant-isolated region of a GaAs/AlGaAs heterostructure between 25 and 295 K. Current conduction was dominated by bulk rather than metal contact limited effects. Bulk conduction in the implant-isolated region is due to several different mechanisms; at low electric fields a resistive current; at low temperatures and high electric fields, field ionization current proportional to V2 exp(−V0/V); and at high temperatures and high electric fields, Poole–Frenkel conduction proportional to V exp(aV1/2/rkT−qφb/rkT). The resistive current can further be separated into two components, one of which dominates at low temperatures and is proportional to V exp(−B/T1/4), and the other which dominates at high temperatures and is proportional to V exp(−Ea/kT). These results are applicable to any GaAs-based structure rendered semi-insulating by an isolation implant, and describe the current conduction characteristics from zero bias to breakdown. Such a description is critical to understanding leakage currents in GaAs/AlGaAs devices such as high-performance heterojunction bipolar transistors, field-effect transistors, and laser diodes that commonly employ implant isolation as a part of the fabrication process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355119
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 152
    Electronic Resource
    Electronic Resource
    Defects and ion redistribution in implant-isolated GaAs-based device structures (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6580-6586 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Implant isolation of thick GaAs based epitaxial structures using either multiple energy keV ions or a single MeV ion implantation is becoming more popular for devices such as heterojunction bipolar transistors or quantum well lasers. We report examples of both types of isolation schemes, using keV F+ and H+ ions, or MeV O+ ions. Post-implant annealing at temperatures in the range 500–600 °C is needed to maximize the resistivity of the implanted material, but this causes redistribution of both F and H (but not O) and accumulation of hydrogen at strained or ion-damaged interfaces. The amount of hydrogen motion is sufficient to cause concerns about dopant passivation occurring in the initially masked, active regions of the devices. The resistance of the ion-implanted regions is stable for periods of ≥50 days at 200 °C, and is controlled by deep level point defects which pin the Fermi level near mid gap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355096
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 153
    Electronic Resource
    Electronic Resource
    Measurement of ion induced damage-profiles in GaAs (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6587-6591 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this study, with the use of a sensitive optical technique, we demonstrate the possibility of measuring the depth distribution of damage in GaAs that is generated by various ion-assisted processes such as ion implantation and ion assisted plasma etching. We have used this technique to measure the depth distribution of damage in both He and Ar implanted GaAs and in inert gas and reactive ion etched GaAs. The sensitivity of the technique allowed us to measure damage profiles over a large range of ion energies and ion doses. We have also confirmed previously published results indicating that damage created by sputter etching is inversely proportional to the mass of the ions used in the etching process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355337
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 154
    Electronic Resource
    Electronic Resource
    Pulsed laser-induced melting followed by quenching of silicon films (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6592-6598 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphization and crystallization were studied through laser-induced melting of silicon films formed on quartz substrates induced by irradiation with a 30 ns XeCl excimer laser. Homogeneous and rapid solidification occurs and amorphous solid state can be formed when the melt duration is long enough to make the temperature gradient in liquid silicon lower than 1×105 K/cm at the Si/quartz interface. The solid state after homogeneous solidification is governed by recalescence caused by latent heat released at solidification. A completely amorphous state is formed when film thickness is thinner than 24 nm because latent heat reduces as film thickness decreases. Both crystalline and amorphous states were observed for film thickness above 24 nm because recalescence can cause crystalline grain growth. Complete crystallization occurs through interface controlled growth when the temperature gradient is higher than 1×105 K/cm. The velocity of liquid/solid interface is 0.6 m/s, which is too low to cause amorphization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355097
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 155
    Electronic Resource
    Electronic Resource
    Raman investigation of the nonlinear optical phenomenon of polarization rotation in Ti:LiNbO3 channel waveguides (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1492-1500 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The nonlinear phenomenon of polarization rotation in Ti:LiNbO3 optical channel waveguides was investigated using Raman microprobe microscopy. Polarization sensitive Raman selection rules permitted the identification of polarization rotation of the propagating transverse electric or transverse magnetic waveguide mode. From an analysis of the Raman scattered light collected orthogonal to the waveguide surface the threshold power necessary to initiate the process of mode conversion could be determined. In addition, the Raman microprobe was used to determine waveguide loss coefficients by collecting inelastically scattered light. The values obtained by this method were compared to those measured by collecting the elastically scattered light. A value for the asymmetric component, β15, of the photovoltaic tensor was calculated to be 7.8×10−13 A/W for the X-cut, Y-propagating and 3.8×10−14 A/W and 1.2×10−14 A/W for the rapid thermally annealed Z-cut, Y-propagating channel waveguides, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354848
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 156
    Electronic Resource
    Electronic Resource
    Simulation and analysis of silicon electro-optic modulators utilizing the carrier-dispersion effect and impact-ionization mechanism (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1521-1528 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A new type of Si guided-wave electro-optic modulator is proposed and analyzed. The modulator makes use of the impact-ionization mechanism for carrier generation, and the carrier-dispersion effect for electro-optic conversion. Both electrical and wave propagation properties of the modulator were examined by a two-dimensional device simulator and a three-dimensional waveguide simulator, respectively. Numerical estimates of phase modulation due to refractive-index change and intensity modulation due to optical absorption and radiation loss were obtained. One of important features of the prospected modulator is speed. The simulated turn-on and turn-off time of the modulator was less than 1 ns. GHz modulation is, therefore, possible for this class of modulators with device structure and doping profiles optimized for fiber coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354851
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 157
    Electronic Resource
    Electronic Resource
    Thermal diffusivity measurements on solids using collinear mirage detection (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1539-1547 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A report on the adequacy of the collinear mirage technique for thermal diffusivity measurements on bulk homogeneous solids is presented. A 3D theoretical model for collinear deflection has been developed from which two simple linear relations between measurable parameters and the thermal diffusivity have been obtained. Two methods, the so-called zero-crossing and phase methods, are discussed in detail. The second one seems to be a promising tool for thermal diffusivity determination. It has been validated by means of experimental measurements on a set of samples with known thermal diffusivities. The technique is restricted to semitransparent solids but is also valid for materials with either high or low thermal diffusivities, being specially useful for this last group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354854
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 158
    Electronic Resource
    Electronic Resource
    Effect of H on Si molecular-beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6615-6618 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In Si crystal growth by molecular-beam epitaxy (MBE) at low temperatures there is known to be an epitaxial thickness: an initially crystalline regime before the deposited film becomes amorphous. The predominant impurity in MBE is hydrogen, but the role of background H in low-temperature MBE has not previously been assessed. Here the effect of deliberate dosing of the Si surface with atomic H during low-T growth is studied. The epitaxial thickness is shown to be sensitive to very small additional H fluxes (≈10−9 Torr, i.e., an increase in H only marginally above ambient). With further increases in dose rate, the epitaxial thickness decreases as hepi=h0−k(ln PH). Using secondary-ion-mass spectrometry data on the segregated H at the interface, we argue that breakdown in epitaxy is not caused directly by the surface concentration of adsorbed impurities. It is deduced that very small concentrations of H may influence the Si surface diffusion rate. The possible effect of background H adsorption on previous experiments on Si steps and surface diffusion is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 159
    Electronic Resource
    Electronic Resource
    Annealing of silicon implanted by a high dose of cobalt ions investigated by in situ x-ray diffraction (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1590-1596 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A silicon wafer was implanted by a high dose of cobalt ions. Afterwards it was annealed in situ while grazing incidence x-ray diffraction measurements in a temperature range up to 690 °C were carried out. The formation of cobalt disilicide (CoSi2) precipitates starts during implantation. The annealing dependence of the precipitate growth, of strain relaxation, and of improvements of the silicide crystallinity was determined. We got an activation energy of (0.47±0.08) eV for the observed annealing process. The result is a buried cobalt disilicide layer with very rough interfaces. The film quality can be improved by a subsequent annealing at about 1000 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354832
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 160
    Electronic Resource
    Electronic Resource
    Ion implantation and dry etching characteristics of InGaAsP (λ=1.3 μm) (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1610-1615 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical activation characteristics of Si+ and Be+ ions implanted into InGaAsP (λ=1.3 μm) grown lattice matched to InP by metalorganic molecular beam epitaxy were studied as a function of ion dose (5×1012–5×1014 cm−2), annealing time (3–60 s) and annealing temperature (575–750 °C). Maximum doping concentrations of ∼2×1019 cm−3 were obtained for both Si+ and Be+, with activation energies for electrical activation of 0.58 and 0.39 eV, respectively. Multiple energy F+ or H+ implants can be used to produce high resistance layers for isolation purposes—maximum sheet resistances of ∼8×106 Ω/(D'Alembertian) or ∼106 Ω/(D'Alembertian) for initially p+ or n+ InGaAsP, respectively, were obtained for F+ implants followed by annealing near 450 °C. Smooth, anisotropic dry etching of the InGaAsP is obtained with electron cyclotron resonance CH4/H2/Ar discharges at low dc biases. The etch rates are the same for both n+ and p+ quaternary layers and are independent of the doping level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354809
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 161
    Electronic Resource
    Electronic Resource
    Radiation damage behavior of LiNbO3 crystal by MeV F ion implantation (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1625-1628 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X, Y, and Z crystalline cut LiNbO3 crystals were implanted by 1.0 MeV F ions with a dose of 1×1015 ions/cm.2 The virgin and implanted LiNbO3 crystals were investigated using the Rutherford backscattering/channeling technique. The obtained minimum yields of virgin crystals were 4%, 8%, and 6% for X-, Y-, and Z-cut LiNbO3 crystals, respectively, because of their different arrangements of lattice sites in channeling direction. The measured damage profiles are also influenced by the arrangement of lattice sites in channeling measurements. The damage profiles of X-cut LiNbO3 crystal induced by 1.0 MeV F+ at a fluence range of 1×1014–3×1015 ions/cm2 have been studied and compared with the Transport of Ions in Matter, version 1990 calculation. It has been found that not only the nuclear energy deposition but also the electronic energy deposition influences the defect production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354811
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 162
    Electronic Resource
    Electronic Resource
    Stability analysis of numerical solutions of wave propagation when pseudoviscosity is replaced by real viscosity (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1649-1651 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The artificial viscosity method was originally introduced by Von Neuman and Richtmeyer [R. D. Rchtmeyer and K. W. Morton, in Difference Methods for Initial Value Problem (Interscience, New York, 1967)] to spread the shock over several cells of the mesh. This method is useful if the physical phenomena present in the shock front are not of interest. In some cases, such as polymer, the amount of viscosity is large enough to spread the front shock naturally. In our problem, pseudoviscosity is ignored. A stability analysis shows that the time step restrictions for stability can be less stringent than with pseudoviscosity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354815
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 163
    Electronic Resource
    Electronic Resource
    Ion-beam adhesion effects in the Cu/sapphire interfacial system (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1670-1674 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of 2 MeV H+ , B+, O++, and Au++ ion irradiation on the adhesion energy of thin Cu films deposited on sapphire has been investigated. Adhesion energy was measured by the observation of the resultant laterally segregated Cu particle shape after vacuum annealing. Film/substrate adhesion is shown to increase with increasing ion dose and exhibits saturation behavior at high fluences. The adhesion energy is shown to be a linear function of the electronic stopping over the entire ion mass range—suggesting a purely electronic mechanism for the adhesion enhancement in this ion energy regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354819
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 164
    Electronic Resource
    Electronic Resource
    Structural and electrical properties of reactively sputtered InN thin films on AlN-buffered (00.1) sapphire substrates: Dependence on buffer and film growth temperatures and thicknesses (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1684-1691 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An extensive investigation of InN overlayers on AlN-buffered (00.1) sapphire by reactive magnetron sputtering has been undertaken and the dependencies of several basic materials properties (film thickness, development and quality of heteroepitaxy, film morphology, and electrical transport) on such key deposition parameters such as the growth temperatures of the insulating AlN buffer layer and the InN overlayer and their thicknesses have been determined. Three prominent effects of the AlN buffer layer are (1) the stabilization of heteroepitaxial growth over a broad range of film and buffer layer growth temperatures; (2) the attainment of a higher Hall mobility (up to 60 cm2/V s) over much of the same range; and, (3) the retention of heteroepitaxial growth, higher Hall mobility, and pseudo-two-dimensional growth even in the limit of an InN layer of ∼40 A(ring). In the context of a structure-zone model, the AlN buffer layer is projected to effectively raise the growth temperature of the InN thin film. The increase in effective growth temperature is, however, insufficient to overcome low atomic and cluster mobility and to achieve single-crystal InN thin film growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354822
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 165
    Electronic Resource
    Electronic Resource
    Re-evaporation effects and optical properties of molecular-beam-epitaxial AlGaAs/GaAs/AlGaAs wells (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1697-1699 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Elemental materials that condense on surfaces near effusion cells can be reevaporated toward substrates when heated by radiation from effusion furnaces. There they accumulate as unwanted impurities at interfaces and distribute throughout epitaxial films during growth. This effect is greatly increased when shutters are closed. Re-evaporated aluminum is shown to degrade minority-carrier properties of Al0.3Ga0.7As/GaAs double heterostructures. Modified temperature schedules and hardware to reduce re-evaporation effects are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354823
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 166
    Electronic Resource
    Electronic Resource
    Measurement of thermal stress and stress relaxation in confined metal lines. I. Stresses during thermal cycling (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1716-1724 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method based on the bending beam technique has been developed to measure the thermal stresses of fine lines confined by a dielectric layer. This method has been employed to determine the thermal stress of Al (2 at. % Cu) lines passivated by a SiO2 overlayer between room temperature and 400 °C. The effect of quartz confinement was analyzed by matching the thermal displacement at the metal/passivation interfaces and by imposing a mechanical equilibrium condition on the structure. The analysis enables us to deduce the triaxial stress components of metal and passivation from measurements of the substrate bending parallel and perpendicular to the length direction of the lines. Results of the measurements show a substantial stress enhancement as a result of the confinement, with the stress level significantly higher than that of a passivated blanket film. Parameters that influence the magnitude of the stress components are line geometry, layer deposition conditions, and the extent of plastic deformation during thermal cycling. Results of the measurements are consistent with those determined using x-ray techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354826
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 167
    Electronic Resource
    Electronic Resource
    Influence of mismatch on the defects in relaxed epitaxial InGaAs/GaAs(100) films grown by molecular beam epitaxy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1731-1735 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thick (∼3 μm) films of InxGa1−xAs grown on GaAs(100) substrates, across the whole composition range, have been examined by transmission electron microscopy and double-crystal x-ray diffraction. The results were compared with the observed growth mode of the material determined by in situ reflection high-energy electron diffraction in the molecular beam epitaxy growth system. The quality of the material degraded noticeably for compositions up to x∼0.5 associated with an increased density of dislocations and stacking faults. In contrast, improvements in quality as x approached 1.0 were correlated with the introduction of an increasingly more regular array of edge dislocations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354827
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 168
    Electronic Resource
    Electronic Resource
    A macroscopic model for focused-ion-beam-induced deposition (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1762-1769 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A time-dependent model for focused-ion-beam-induced deposition is presented which explicitly takes the scanning strategy of the beam during deposition into account. The model differentiates between the contribution of the beam center and that of the beam wings, and contains all major experimental variables such as current density, focus size, scan speed, and frame time. The deposition rate has been measured for tungsten as a function of the major experimental variables. The model has been fitted to these data and is found to describe the various dependences very well. By use of the model inclusive of the parameters obtained from the fit, we can predict optimum deposition conditions. Furthermore, the model clarifies effects observed during deposition on the structured surface of an integrated circuit, such as redeposition of sputtered material and poor step coverage due to an impeded gas flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354805
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 169
    Electronic Resource
    Electronic Resource
    Optical absorption spectrum of hydrogenated amorphous silicon using photo-pyroelectric spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1799-1804 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical absorption coefficient α of doped and undoped hydrogenated amorphous silicon (a-Si:H) has been measured for photon energies from 2.2 to 1.0 eV using photo-pyroelectric spectroscopy (PPES). A simplified experimental setup and analysis for extracting α from the PPES data are described. In PPES the temperature rise induced in the a-Si:H thin film due to weakly absorbed light is detected via a pyroelectric polymer in thermal contact with the sample. This technique presently has a sensitivity of αd(approximately-greater-than)10−3, where d is the sample thickness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354784
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 170
    Electronic Resource
    Electronic Resource
    Magnetotransport and magneto-optical properties of δ-doped InSb (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1793-1798 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results of Shubnikov–de Haas (SdH), cyclotron resonance (CR), and Hall-effect measurements on δ-doped InSb:Si films grown by molecular-beam epitaxy on insulating InP substrates are reported. The investigation covers samples with sheet densities of Si dopant atoms ranging from 1×1011 to 1×1013 cm−2, temperatures from 4.2 to 300 K, and fields from 0 to 7 T. The SdH oscillations show that the samples contain electrons of two-dimensional nature, occupying multiple subbands. The effective masses obtained from the CR data correspond well to the subband occupation densities. The Hall measurements as well as the CR experiments also give evidence for the presence of additional electrons, with the conduction-band-edge mass m*=0.014m0 of bulk InSb, which exist presumably in the bulk of the films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354783
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 171
    Electronic Resource
    Electronic Resource
    Characterization of trapping states in polycrystalline-silicon thin film transistors by deep level transient spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1787-1792 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Polycrystalline-silicon (poly-Si) thin film transistors (TFTs) have been assessed using deep level transient spectroscopy (DLTS) based on the measurement of current transients due to the thermal emission of carriers trapped at deep levels in the poly-Si. Measurements were made on fully hydrogenated TFTs and the DLTS signal was found to vary continuously between 77 K and room temperature, without showing the characteristic peaks normally associated with point defects in single crystal Si. This demonstrates the existence of a continuous distribution of states through the band gap rather than discrete monoenergetic states. Analysis of the DLTS signal suggests the density of states increases rapidly toward the conduction band edge indicating the presence of a relatively high density of tail states. After annealing the TFTs at 450 °C the current DLTS signal was found to increase due to an increase in trap state density, which occurs because Si–H bonds are thermally unstable at this temperature. The increase in signal was over the whole temperature range of the measurement showing that hydrogen passivates states up to at least 0.1 eV below the conduction band as well as states nearer mid-gap. The effects of varying the fill voltage on the measurement and the time dependence of the current transient were also investigated and added weight to arguments that the current transient was due to the thermal emission of carriers trapped at deep levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354782
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 172
    Electronic Resource
    Electronic Resource
    Optical and transport properties of single quantum well infrared photodetectors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1826-1831 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have performed an extensive series of measurements on symmetrical barrier bound-to-continuum and asymmetrical barrier bound-to-bound quantum well infrared photodetectors consisting of only a single well. We find that the behavior of the optical (e.g., responsivity) and transport properties (e.g., gain) as a function of bias is strikingly different from that of the usual multi-quantum well detectors. The simplicity of the structure has allowed an accurate theoretical calculation of the potential drops across each barrier, the photoinduced carrier depletion in the quantum well and therefore a detailed understanding of the device physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354789
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 173
    Electronic Resource
    Electronic Resource
    Effective conductivity of composites containing spheroidal inclusions: Comparison of simulations with theory (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1844-1854 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We determine, by first-passage-time simulations, the effective conductivity tensor σe of anisotropic suspensions of aligned spheroidal inclusions with aspect ratio b/a. This is a versatile model of composite media, containing the special limiting cases of aligned disks (b/a=0), spheres (b/a=1), and aligned needles (b/a=∞), and may be employed to model aligned, long- and short-fiber composites, anisotropic sandstones, certain laminates, and cracked media. Data for σe are obtained for prolate cases (b/a=2, 5, and 10) and oblate cases (b/a=0.1, 0.2, and 0.5) over a wide range of inclusion volume fractions and selected phase conductivities (including superconducting inclusions and perfectly insulating "voids''). The data always lie within second-order rigorous bounds on σe due to Willis [J. Mech. Phys. Solids 25, 185 (1977)] for this model. We compare our data for prolate and oblate spheroids to our previously obtained data for spheres [J. Appl. Phys. 69, 2280 (1991)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354792
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 174
    Electronic Resource
    Electronic Resource
    Photoelectric study of β-FeSi2 on silicon: Optical threshold as a function of temperature (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1138-1142 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Investigation of the photoelectric properties of several metal/β-FeSi2/Si heterostructures is presented. For thin silicide samples (200 A(ring)), the photocurrent follows a Fowler's law with a threshold Φ1 lower than the silicide band gap Eg. For thicker silicide samples (2500 A(ring)), the behavior of the photocurrent is different because the optical absorption within the silicide can no longer be neglected: a maximum of the photocurrent is observed instead at Eg. The variations of Eg and Φ1 with temperature are compellingly similar and show the strong effect of the electron-phonon coupling. We suggest that the threshold Φ1 corresponds to transitions between a trap localized near the heterojunction and the silicide conduction band.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354939
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 175
    Electronic Resource
    Electronic Resource
    Thermally activated real-space-transfer noise in pseudomorphic high-electron-mobility transistors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1143-1150 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The low-frequency (0.5 Hz≤f≤100 kHz) noise characteristics of AlGaAs/InGaAs/GaAs pseudomorphic high-electron-mobility transistors at temperatures from 3.8 up to 300 K are reported. Between 100 and 200 K the noise spectra are dominated by an intense thermally activated contribution, due to electron transfer from InGaAs to AlGaAs (real-space transfer) and vice versa. Its spectral shape is significantly broader than a pure Lorentzian and results from a distribution of associated time constants. This is interpreted in terms of an inhomogeneous barrier height at the AlGaAs/InGaAs interface with a half-width at half-maximum of 29.3±0.8 meV. It is proposed that random disorder in alloy composition and the concomitant fluctuations in the conduction-band discontinuity along the channel give rise to such a spread in barrier heights.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354914
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 176
    Electronic Resource
    Electronic Resource
    Electrical and structural properties of dislocations confined in a InGaAs/GaAs heterostructure (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6720-6725 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electrical activation and structural defects in lattice-mismatched InGaAs/GaAs heterostructures are studied using the capacitance-voltage method, deep-level transient spectroscopy, and cross-sectional transmission electron microscopy. Confinement of structural defects is observed in an In0.2Ga0.8As/GaAs heterostructure with a relaxed InGaAs layer thicker than the thickness of the critical layer. When In composition is 0.2, where the lattice mismatch is 1.4% between InGaAs and GaAs, a two-dimensional growth mode dominates. Misfit dislocations are formed and conduction electrons are depleted only near the InGaAs/GaAs interface. Carrier depletion is related to an electron trap with an activation energy of 0.395 eV and a capture cross section of 1×10−16 cm2 induced by deformation. Electrical evaluations show that electrical activity in the InGaAs layer does not degrade by interfacial dislocations. Therefore, a good-quality InGaAs layer is provided though the thin layer near the interface is of poor quality. These results indicate that elastic strain is not large enough in this system for dislocations to rise to the surface. In an In0.4Ga0.6As/In0.2Ga0.8As/GaAs heterostructure, however, dislocation confinement is imperfect in spite of similar lattice mismatches between each of the interfaces. In this structure, threading dislocations rise into the epitaxial layer not only from the In0.4Ga0.6As/In0.2Ga0.8As interface but also from the In0.2Ga0.8As/GaAs interface. This indicates that dislocations can be generated in the layer that had already been formed during the growth of an upper layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355068
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 177
    Electronic Resource
    Electronic Resource
    The effect of growth temperature on the electrical properties of AlInAs/InP grown by molecular beam epitaxy and metal-organic chemical-vapor deposition (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6726-6733 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al0.48In0.52As layers grown on n+-InP substrates by molecular beam epitaxy (MBE) and metal-organic chemical-vapor deposition (MOCVD), as a function of substrate temperature, have been characterized by current-voltage-temperature, capacitance-voltage, deep-level transient spectroscopy, and admittance spectroscopy measurements. It was found that for diodes formed on MOCVD-AlInAs the current in forward bias is dominated by thermionic emission and the reverse current by recombination through the residual midgap states; whereas, for MBE-AlInAs diodes, the respective currents are dominated by defect-assisted tunneling at low forward and reverse biases. Schottky barrier heights were found to decrease with decreasing growth temperature. Three defect levels E1, E2, and E3 were observed in both material systems, and their densities were found to increase rapidly from ∼1012 to ∼1016 cm−3 as the growth temperature decreased from 740 to 500 °C. The decrease of barrier height and the appearance of the defect-assisted tunneling current at low bias were found to correlate with the increase of defect density. The high density of defects may be responsible for the low barrier heights and higher leakage currents previously observed in AlInAs/InGaAs/InP high electron mobility transistors though MOCVD growth provided high quality AlInAs layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355069
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 178
    Electronic Resource
    Electronic Resource
    The influence of the strain-induced electric field on the charge distribution in GaN-AlN-GaN structure (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6734-6739 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that strongly pronounced piezoelectric properties play a key role in GaN-AlN-GaN semiconductor-insulator-semiconductor (SIS) and related structures. In sufficiently thin AlN layers, the lattice constant mismatch is accommodated by internal strains rather than by the formation of misfit dislocations. These lattice-mismatch-induced strains generate polarization fields. We demonstrate that, in a GaN-AlN-GaN SIS structure with the growth axis along a (0001) crystallographic direction, the strain-induced electric fields can shift the flat band voltage and produce an accumulation region on one side and a depletion region on the other side of the AlN insulator. On which side of the insulator the accumulation region is produced depends on the type of atomic plane at the heterointerface (Ga or N). The surface charge density caused by the piezoeffect is on the order of 1012 cm−2. As a consequence of the asymmetry in the space charge distribution, the capacitance-voltage (C-V) characteristics of the SIS structure become asymmetrical. The asymmetrical shift of the C-V characteristics with respect to the origin is on the order of 1.5 V for a 30 A(ring) AlN film. This asymmetry should vanish in a relaxed film. Hence, capacitance-voltage measurements of GaN-AlN-GaN SIS structures can be used for quantitative characterization as to the degree of AlN film relaxation, depending on the film thickness. This and related techniques should become important tools for the characterization of piezoelectric layered semiconductor films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355070
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 179
    Electronic Resource
    Electronic Resource
    The achievement of near-theoretical-minimum contact resistance to InP (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6740-6746 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the electrical and metallurgical behavior of the InP/Au/Ni contact system. We show that when a layer of Au, 100 A(ring) or more in thickness, is introduced between n-InP and Ni contact metallization, specific contact resistivity Rc values in the low 10−8 Ω cm2 range are achieved after sintering. It is suggested that these ultralow values of Rc are due to the presence, at the metal-InP interface, of a Ni3P layer combined with a stoichiometry change in the InP surface. We show, in addition, that it is possible to achieve very low Rc values with this system without incurring device destroying sinter-induced metallurgical interdiffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355071
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 180
    Electronic Resource
    Electronic Resource
    A theoretical investigation on the quantum field effect directional coupler (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6747-6753 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A theoretical investigation on the quantum field effect directional coupler is presented. The behavior of electrons in the device is studied by solving the Schrödinger equation directly. The complete transfer effect is revealed to be an intrinsic property of the parity symmetry of the system. Transfer length is precisely calculated by using the transfer matrix method. Two model transverse confinements have been used in the calculation. One is a symmetric double rectangular well; and the other is a symmetric double finite-parabolic potential. Conductance of the device is investigated by applying the Landauer formula. Conductance oscillations with Fermi energy and barrier height are obtained. One method of determining the transfer length from the curve of conductance vs barrier height is proposed. Special attention is paid to the multimodedness of the device. Correlation among the different modes is demonstrated to reduce the transfer effect of the device. Reflection at the interfaces between uncoupled and coupled waveguides is proved to be negligible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355072
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 181
    Electronic Resource
    Electronic Resource
    Evaluation of silicon-on-insulator substrates using photoconductive frequency resolved spectroscopy (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6754-6758 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe here the application of photoconductive frequency resolved spectroscopy to determine excess carrier lifetime distributions and carrier kinetics in SIMOX (separation by implanting oxygen) material. In order to evaluate the influence of the implant and anneal processes on the quality of the silicon overlayer we have also analyzed unprocessed bulk silicon, high temperature annealed bulk silicon and as-implanted SIMOX material. Our photoconductive frequency resolved spectroscopy results reveal that the SIMOX layers have a higher density of defects than standard device quality silicon substrates. Characteristic parameters of the dominant traps in these materials have been obtained from Arrhenius plots of the lifetime distributions. The defects found in these SIMOX layers are shown to be formed during the high temperature anneal stage of the material production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355073
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 182
    Electronic Resource
    Electronic Resource
    Critical currents of ceramic superconductors induced by pulsed magnetic fields (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6759-6766 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We attempted to measure the critical current density Jc of ceramic superconductors with pulsed magnetic fields. Using a pair of search coils coaxially mounted just below a ring sample, we measured induced signals that were considered to be proportional to the time derivative of the sample magnetization. Four samples were used: YBa2Cu3Oy, YBa2Cu4Oy, Bi2Sr2CaCu2Oy, and Bi1.6Pb0.4Sr2Ca2Cu3Oy. These were all synthesized by the polymerized complex method. It was found that the induced signals from the paired search coils are typically of two types. One shows a monotonic decrease to zero as a function of time. The other has a minimum at a certain time and then approaches zero. The observed signals were simulated in the framework of the Bean model and the Kim–Anderson model for critical current density. Theoretical profiles by these two models reproduce the observed results well and suggest that the two types of induced signals are the same in appropriate limits. We discuss how to evaluate Jc from the observed signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355074
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 183
    Electronic Resource
    Electronic Resource
    Chemical and compositional changes induced by N+ implantation in amorphous SiC films (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2013-2020 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of 30 keV N+ implantation in amorphous silicon carbide films deposited on silicon substrates by rf sputtering over a fluence range of 1×1016–2×1017 ions cm−2, are studied by means of x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and infrared (IR) absorption techniques. The ion-induced modifications of these films have been investigated on the basis of the chemical state evolution of Si, C, and N (using XPS and AES) and on the basis of the vibrational features of the films components (using IR absorption). The results show that implanted N bonds Si selectively, substituting the C atoms in the silicon carbide, and the C substitution by N results in a composite layer of carbonitrides and free C. An ion-induced C transport has also been observed and correlations are established between the formation of silicon carbonitrides and the dynamical behavior of the C in the implanted layer. The latter appears as a superposition of (a) a chemically induced atomic redistribution, required by local stoichiometry and space-filling possibilities in an amorphous network, and (b) a radiation-induced redistribution, a mechanism that is prevailing at low-fluence implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354764
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 184
    Electronic Resource
    Electronic Resource
    Structural evolution of mechanical alloyed Fe-Al powders after consolidation and thermal ageing (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2053-2057 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Elastic energy dissipation and dynamic Young's modulus measurements coupled with x-ray and energy-dispersive analyses were employed to follow the structural transformation of bulk samples prepared by mechanical alloying Fe-Al powders mixed in the atomic ratio Fe/Al=3. The results show that it is possible to synthesize a nanocrystalline bulk Fe3Al intermetallic phase by properly combining mechanical treatments of the powders with suitable temperature thermal aging. Driving mechanisms and transformation paths leading to this stable phase, not otherwise observed in the simply thermally aged Fe-Al crystalline powders, are examined and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354769
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 185
    Electronic Resource
    Electronic Resource
    Preparation of copper indium diselenide by selenization of copper indium oxide (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2046-2052 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A process is reported for preparation of thin films of copper indium diselenide (CIS). This process involves two steps: (a) formation of Cu2In2O5 by spray pyrolysis and (b) reaction of Cu2In2O5 with selenium vapor to form CIS. The purity of the CIS prepared by this method can approach that of the material prepared by vacuum deposition methods because highly purified water and nitrate salts can be used in the spray pyrolysis step, and the purity of the selenium used in the second step can be identical to that used in any of the vacuum processes. This two-step process appears to have general applicability; we have been able to prepare a variety of sulfides and tellurides in addition to selenides. The advantage of this process is that any metal ion added to the spray solution is incorporated in the oxide and remains in the selenide after the selenization. Comparison of the Cu/In ratios of the selenide films with those of the precursor oxide films shows that there was a slight decrease in the copper content when the oxide was converted to the selenide. The consistency of the composition of the films prepared at 400 °C is comparable to that of films prepared by the other methods such as thermal processing of elemental layers and reactive sputtering of Cu and In with selenium vapor. Auger composition studies indicated that selenium substitution occurred stepwise. The x-ray-diffraction data for CIS were consistent with a chalcopyrite phase. The data for the resistivity and Hall-effect measurements at room temperature indicated a marked dependence of the resistivity and the hole density on the Cu/In atomic ratio. When this ratio was around 1.45, the resistivity had low values around 30 Ω cm, and the hole density was in the 1017 cm−3 range. A direct band gap of 0.95 eV was determined from the optical-absorption spectrum of this material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354768
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 186
    Electronic Resource
    Electronic Resource
    Morphology and transport of YBa2Cu3O7−x sputtered in argon, oxygen, and hydrogen: Dependence on deposition temperature (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6780-6787 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: YBa2Cu3O7−x films have been deposited on MgO by reactive, off-axis magnetron sputtering in an argon, oxygen, and hydrogen gas mixture. The material and electrical properties of the films were studied for deposition temperatures from 600 to 760 °C. The films, all approximately 300 nm thick, were predominantly a-axis oriented when deposited at or below 620 °C but were c-axis oriented when deposited at temperatures above 640 °C. The surfaces of films deposited between 640 and 710 °C were partially covered with a-axis grains. Surface roughness measurements indicated the smoothest films occurred for deposition temperatures below 680 °C. Resistance ratios as great as 3.1 were observed for some films. Transition temperatures exceeded 89 K and resistivities at 100 K were less than 150 μΩ cm for the best films. Low-temperature critical current densities exceeded 107 A/cm2 for films deposited from 640 to 720 °C. The temperature dependence of the critical current density near the transition temperature had a power law dependence of nearly 3/2 for deposition temperatures below 690 °C. The power law dependence decreased for increasing deposition temperatures, dropping to nearly 1.1 in the film deposited at 750 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355077
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 187
    Electronic Resource
    Electronic Resource
    X-ray refinement and magnetic properties of nitrogenated melt-spun Sm2Fe17 compound (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6824-6829 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sm2Fe17N2.9 compound powders were prepared from parent alloys of Sm2Fe17 which were made by both the arc-melting and rapid solidification processes. The cast Sm2Fe17 contained mixed phases of SmFe3 and α-Fe, and correspondingly formed less Sm2Fe17Nx with a rather large amount of residual α-Fe after nitrogenation. The melt-spun Sm2Fe17 compound, however, was single phase and exhibited a negligible amount of residual α-Fe after nitrogenation. The residual amount of free iron was found to increase as a function of milling time and impede the development of promising permanent magnetic properties. The melt-spun Sm2Fe17Nx compound powders exhibited a coercivity value iHc of 5 kOe, which is double that of the as-cast Sm2Fe17Nx powders and a high remanence, Br=60 emu/g. The average magnetic moment of Fe atoms in the crystal is estimated to be 2.29 μB and the Fe atom in the 6c site shows the highest magnetic moment of 2.65 μB. The expansion in the c-axial direction of the nitrogenated crystal was found to be mainly due to extension of Sm(6c)-Fe(6c) and Fe(18f)-Fe(18f) distances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355082
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 188
    Electronic Resource
    Electronic Resource
    Combined three-axis surface magneto-optical Kerr effects in the study of surface and ultrathin-film magnetism (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6810-6823 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Surface and ultrathin-film magnetocrystalline anisotropy in epitaxial fcc Fe thin films grown on room-temperature Cu(100) single crystals has been investigated, in situ, by the combined surface magneto-optical Kerr effects (SMOKE). In polar, longitudinal, and transverse Kerr effects, the direction of the applied magnetic field must be distinguished from the direction of magnetization during the switching process. For arbitrary orientations of the magnetization and field axis relative to the optical scattering plane, any of the three Kerr effects may contribute to the detected signal. A general expression for the normalized light intensity sensed by a photodiode detector, involving all three combined Kerr effects, is obtained both in the ultrathin-film limit and for bulk, at general oblique incidence angles and with different orientations of the polarizer, modulator, and analyzer. This expression is used to interpret the results of fcc Fe/Cu(100) SMOKE measurements. For films grown at room temperature, polar and longitudinal Kerr-effect magnetization loops show that the easy axis of magnetization rotates from the (canted) out-of-plane direction to the in-plane direction at a thickness of about 4.7 monolayers. Transverse Kerr-effect measurements indicate that the in-plane easy axes are biaxial.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355081
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 189
    Electronic Resource
    Electronic Resource
    Studies on the relation between the eigenvalue and enhancement of Kerr effect for magneto-optical materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6830-6839 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on the universal additivity law of the interference of light the following was achieved. (i) An analytic representation between the eigenvalue of the Kerr rotation angle θ0k and the enhanced θk for a double-layered film, θk=en1 θ0k, was obtained theoretically, where e is the enhancement factor and n1 is the refractive index of the dielectric medium. (ii) An analytic representation between θk and θ0k (θk=e013e123n2θ0k) of the trilayered film [bilayered transparent media and monolayered magneto-optical (MO) medium], was also obtained, where e013 and e123 are the enhancement factors: The calculated θk value is in good agreement with experimental results for e=1. In general, the theoretical calculation shows that θk is related to the thickness of the transparent media. Thus, if one wants to get an optimum value for θk, the thickness of the first transparent film layer (such as a glass substrate) must be selected carefully. It also shows that if the variation of the thickness of the glass substrate is 5 nm, θk could vary by 0.1° for MnBiCe films. (iii) The relation connecting θk with θ0k1 and θ0k2 for bilayered MO films has been theoretically studied, where θ0k1 and θ0k2 are the eigenvalues of the Kerr rotation angle of MO materials 1 and 2, respectively. Finally, θk for a Fe/Co film was calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355083
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 190
    Electronic Resource
    Electronic Resource
    Electron-cyclotron-resonance plasma-assisted radio-frequency-sputtered strontium titanate thin films (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6851-6858 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Strontium titanate thin films were deposited by electron-cyclotron-resonance plasma-assisted radio-frequency magnetron sputtering. Electron-cyclotron-resonance plasma assistance was employed because of its ability to be used as a source of low-energy bombardment by a high density of species that are highly activated. It was found that both the structure and composition improve with the application of microwave plasma during the deposition. Analysis of the capacitance-voltage characteristics of metal-insulator-semiconductor devices revealed that the quality of the film/substrate interface is dependent on the pressure, atmosphere, and temperature of the deposition. Interfacial traps which give rise to charged surface states and silicon oxide formation have detrimental effects on films deposited on bare silicon substrates. Films on platinum-coated silicon substrates show good dielectric properties. The small-signal dielectric constant and dissipation factor at a frequency of 100 kHz were 170 and 0.033, respectively. For a 0.37-μm-thick film a charge storage density of 28 fC/μm2 and a unit area capacitance of 3.7 fF/μm2 were obtained at an applied electric field of 200 kV/cm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355086
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 191
    Electronic Resource
    Electronic Resource
    Enhanced refractive index change in asymmetrical quantum wells with an applied electric field (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6872-6875 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We theoretically calculate the electric field induced refractive change index for the ground to first excited state transition in the conduction band of asymmetrical quantum wells. We show that there is a significant change in stark shifts and the refractive index with asymmetry potential. Comparing the results for a square, graded, and step well, it is found that larger refractive index change can be achieved in a step well by a proper choice of the step potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355089
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 192
    Electronic Resource
    Electronic Resource
    Quantitative infrared analysis of the stretching peak of SiO2 films deposited from tetraethoxysilane plasmas (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6876-6882 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared transmission spectra of silicon dioxide (SiO2) thin films (∼4500 A(ring)) prepared by plasma-enhanced chemical-vapor deposition have been quantitatively analyzed. The films were deposited at different substrate temperatures (30–450 °C) using tetraethoxysilane (TEOS)/He, TEOS/He/O2, and TEOS/O2 gas mixtures in a parallel-plate radio-frequency reactor. The infrared transmission fits prove to be very accurate showing evidence of deconvolution into three separated Gaussian profiles to account for the asymmetric line-shape feature of the infrared stretching peak between 950 and 1300 cm−1. The examination of the Fourier transform infrared spectroscopy spectra in the complete frequency range (400–4000 cm−1) and ex situ x-ray photoelectron spectroscopy spectra indicates that some extra structures originate from the incorporation of carbon and hydrogen impurities in the film. As the substrate deposition temperature is increased, impurities are gradually removed from the growing layer. Films deposited at high substrate temperatures reveal a better stoichiometry and present similar deconvolution bands regardless of the gas-phase composition; the corresponding frequencies are shifted to lower energies compared to thermal oxides. In addition, the intensity of the first Gaussian profile, associated with the low-energy asymmetry of the stretching peak, increases with the substrate deposition temperature while the intensity of the third Gaussian profile associated with the presence of the high-energy peak shoulder decreases. The vibrational properties of the film seem to be strongly related to the deposition conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355090
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 193
    Electronic Resource
    Electronic Resource
    Scaling laws for diamond chemical-vapor deposition. I. Diamond surface chemistry (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6888-6894 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simplified model of the gas-surface chemistry occurring during chemical-vapor deposition of diamond thin films is presented. The model results in simple scaling relations, useful for process scale-up and optimization, for growth rate and defect density in terms of the local chemical environment at the substrate. A simple two-parameter expression for growth rate is obtained, which with suitable parameter choices reproduces the results of more detailed mechanisms and experiment over two orders of magnitude in growth rate. The defect formation model suggests that the achievable growth rate at specified defect density scales approximately quadratically with the atomic hydrogen concentration at the substrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355063
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 194
    Electronic Resource
    Electronic Resource
    Die-upset PrCo5-type magnets from melt-spun ribbons (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6907-6911 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We used consolidation (hot pressing) and deformation (die upsetting) techniques to produce magnetically anisotropic permanent magnets from melt-spun PryCo100−y−xCx alloys. The primary phase in these magnets (16≤y≤24 at. %) was the hexagonal PrCo5 phase. The greatest alignment was obtained for low-carbon compositions (0≤x≤2 at. %); in particular, Pr18Co81C produced a remanence of ∼8.7 kG and an energy product of 16.9 MG Oe. The addition of 1 at. % carbon enhanced the coercivity (Hcl≈5.9 kOe) by nearly 80% compared to the carbon-free composition (Hcl≈3.3 kOe). Higher carbon levels (x≥4 at. %) resulted in even larger coercivities (Hcl≥10 kOe) but were accompanied by significantly lower remanences (Br≈6 kG).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355336
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 195
    Electronic Resource
    Electronic Resource
    Neutron scattering investigation of the structure of semiconductor-doped glasses (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6925-6935 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A small-angle neutron scattering (SANS) study of the structure of II-VI semiconductor crystallites in a semiconductor-doped glass is presented. The scattered intensity I(k) exhibits a peak at a nonzero scattering vector and decreases to zero as k goes to zero. The data are interpreted with a simple phenomenological model, based on local mass conservation, which describes a dilute gas of crystallites surrounded by depletion zones. We show that SANS allows a quick and accurate measurement of the average size and of the volume fraction of the crystallites, and we give values of both quantities for a commercial series of glasses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355067
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 196
    Electronic Resource
    Electronic Resource
    Effects of substrate temperature and ion incident energy on silicon surface cleaning using a hydrogen plasma excited by electron cyclotron resonance (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6936-6940 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Effects of the substrate temperature and ion incident energy on silicon surface cleaning and hydrogen penetration caused by irradiation with a hydrogen plasma have been investigated using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. A silicon native oxide and a hydrocarbon-contaminated layer were removed only on the condition that the silicon substrate was struck with hydrogen ions having proper kinetic energies of less than 40 eV at temperatures from room temperature to 400 °C. However, the silicon oxide grew either at temperatures below room temperature or at no ion incidence onto the substrate. This oxidation phenomenon was attributed to residual H2O in the vacuum system. On the other hand, hydrogen penetration occurred only on the condition of hydrogen ion bombardment. The amount of penetrated hydrogen increased with substrate temperature and ion incident energy. The amount of penetrated hydrogen was found to be drastically reduced under the condition of ion incident energy of less than 5 eV and a substrate temperature of about room temperature. It is concluded that an oxideless clean surface without hydrogen penetration into silicon bulk is obtained by means of irradiation with a hydrogen plasma having a low ion incident energy (≤5 eV) at room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355042
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 197
    Electronic Resource
    Electronic Resource
    Isothermal capacitance transient spectroscopy of grain-boundary interfacial states in Bi-doped SrTiO3 ceramics (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2669-2673 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that an isothermal capacitance transient spectroscopy (ICTS) technique is applicable to evaluate the interfacial state of SrTiO3 ceramics. ICTS signals were observed for Bi-doped and undoped SrTiO3 ceramics, and ascribed to interfacial states of grain boundaries. The interfacial states were located at Ei=0.7 eV below the conduction band for the Bi-doped samples and at Ei=0.5 eV for the undoped sample. This result indicates that the dopant bismuth caused deeper interfacial states in energy. The semiquantitative simulation of the ICTS signals suggests that the interfacial density of states of the SrTiO3-Bi2O3 system is more broad compared with other electronic ceramics such as ZnO-Bi2O3 and SiC-BeO systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354659
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 198
    Electronic Resource
    Electronic Resource
    Laser processing of Nb3Al(Ge, Si) high-field superconductors (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2686-2691 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The laser irradiation process is a promising method for the fabrication of metastable Al5–Nb3Al(Ge,Si) compounds. Thereby Nb-sheathed Nb-25 at. % Al(Ge,Si) microcomposite tapes are prepared by a conventional powder metallurgical method and heat treated by a high-intensity CO2-laser beam. The parameters selected during laser beam irradiation of the composite determine the relative amounts of molten, heat-affected or unreacted material. In order to obtain large overall superconducting currents, it is favorable to melt a large fraction of the microcomposite without melting the surrounding Nb sheath. The cooling rate after laser beam irradiation determines the structure and the formation of metastable phases in the resolidifying material. The sequences of the process are simulated by heat flow calculations, which consider laser power, beam diameter, tape velocity, thickness, and microstructure, as well as heat transfer coefficients. From these calculations we could deduce optimum conditions for the laser treatment, leading to Jc values of 105 A cm−2 at 10 T and 104 A cm−2 at 16 T.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354662
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 199
    Electronic Resource
    Electronic Resource
    Magnetic properties and microstructures of the Nd-Fe-B system during the hydrogenation-decomposition-desorption-recombination process (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 2719-2724 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Nd-Fe-B and Nd-Fe-Co-B magnet powders with the high coercivity (≥10 kOe) were obtained by the hydrogenation-decomposition-desorption-recombination (HDDR) process at temperatures between 800 °C and 900 °C. We studied magnetic properties and microstructures of the Nd-Fe-B systems during the HDDR process. The NdH2 phase produced by decomposition of Nd2Fe14BHx with hydrogenation exists in the maze-like form of the size of 10−1 μm. It was found that the size of the NdH2 phase determines the size of the Nd2Fe14B phase formed by the recombination. NdH2, Fe, and Fe2B are more stable than Nd2Fe14B at temperatures from 800 °C to 900 °C. The magnet powders produced by the HDDR process are magnetically almost isotropic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354666
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 200
    Electronic Resource
    Electronic Resource
    Grain-growth process during crystallization of Fe80B20 amorphous alloys (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6988-6989 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is shown that the full isothermal crystallization analysis of Fe80B20 amorphous alloy must include not only a crystal nucleation-and-growth process but also a grain-growth process and that these two processes are separated in time during isothermal annealing. The parameters characterizing the grain-growth process have been found by the fitting calorimetrical signal with the one expected from the normal grain-growth theory. Transmission electron microscopy and selected area electron diffraction seem to confirm our results since they show that there is a good agreement between the average grain radius of crystallization products seen in the micrograph and the one calculated from the obtained parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355051
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...