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
  • 1
    Electronic Resource
    Electronic Resource
    Surface composition and structure of GaN epilayers on sapphire (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 9577-9584 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The surface composition and structure of GaN films grown on sapphire substrates by organometallic vapor-phase epitaxy (OMVPE) have been determined through the use of time-of-flight scattering and recoiling spectrometry (TOF-SARS), classical ion trajectory simulations, and low-energy electron diffraction (LEED). TOF-SARS spectra of scattered and recoiled ions plus fast neutrals were collected using 4 keV Ar+ primary ions. The scattering results were simulated by means of the three-dimensional scattering and recoiling imaging code (SARIC). This data leads to the conclusions that both N-terminated {001¯}-(1×1) and Ga-terminated {0001}-(1×1) surfaces occur, however no evidence was obtained for mixed terminations. No relaxation or reconstruction was detected on either surface, although both surfaces exhibited two structural domains. The {0001¯} surfaces are well-ordered and contained hydrogen atoms bound to the N atoms of the outermost layer. The {0001} surfaces are highly reactive towards adsorption of carbon and oxygen from residual gases, however unlike the {0001¯} surfaces, they adsorb very little hydrogen. These Ga-terminated surfaces are stabilized and obtain more ordered structures as a result of the contamination. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475255
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Gap state distribution in amorphous hydrogenated silicon carbide films deduced from photothermal deflection spectroscopy (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 4319-4325 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The density of gap states distribution in silicon (Si) rich hydrogenated amorphous silicon carbide (a-Si1−xCx:H) films with varying carbon (C) fraction (x) is investigated by the photothermal deflection spectroscopy (PDS). The films are grown using the Electron Cyclotron Resonance Chemical Vapor Deposition (ECR-CVD) technique. By using different methane-to-silane gas flow ratios, a-Si1−xCx:H with x ranging from 0 to 0.36 are obtained. A deconvolution procedure is performed based on a proposed DOS model for these Si rich a-Si1−xCx:H. Good fits between the simulated and experimental spectra are achieved, thus rendering support to the model proposed. Deduction of the DOS enables us to obtain various parameters, including the optical gap and the valence band tail width. The fitted mobility gap Eg is found to be well correlated to the Tauc gap Etauc and E04 gap deduced from the optical absorption spectra. A correlation is also seen between the fitted valence band tail width Evu, the Urbach energy Eu and the defect density. All these parameters are seen to increase with C alloying. A shift in the defect energy level in the midgap with increasing C incorporation is observed, together with a broadening of the defect distribution and a stronger correlation between the defect bands, which can be accounted for in terms of the influence of C dangling bonds on the deep defect density distribution. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448888
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Modeling and analysis of the electron cyclotron resonance diamond-like carbon deposition process (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1634-1639 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond-like carbon (DLC) films were deposited using the electron cyclotron resonance (ECR) chemical vapor deposition process. The behavior of the ECR plasma was formulated using deposition conditions such as microwave power, pressure, and hydrogen/methane (H2/CH4) ratio as input parameters. Thereafter, the outputs were used to formulate a DLC film deposition model, which takes into account the ion bombardment at the film surface, attachment of carbon-carrying ions, and chemisorption of hydrocarbon radicals on the film and hydrogen–surface reactions. The DLC film deposition model suggests that under conditions of high hydrogen atom flux, the main precursors are carbon-carrying ions. Hydrocarbon radicals, such as CH3, only contribute to ∼20% of the total film deposition rate. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1425446
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Characterization of metal-containing carbon films using Raman scattering (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4520-4525 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metal-containing carbon (Me-C:H) films were deposited using the electron cyclotron resonance chemical vapor deposition technique in conjunction with a metal screen-grid system. Four sets of Me-C:H films were analyzed using Raman scattering. Two sets were molybdenum-containing carbon (Mo-C:H) films deposited at fixed dc bias (at different CH4/Ar ratios), and at fixed CH4/Ar ratio (at different dc bias). Another two sets of nickel-containing carbon (Ni-C:H) films were deposited at fixed rf power, but at a different CH4/Ar ratio, with and without postgrowth thermal annealing at 200 °C. All films showed the characteristic G and D peaks except for those with high metal content. The D peak is very pronounced in the Ni-C:H films, and both the G and D peaks follow an opposite trend; downshifting and upshifting in wave number, respectively, as the CH4/Ar ratio was increased. In the case of Mo-C:H films deposited at fixed dc bias, both peaks downshifted in wave number, following an increase in the CH4/Ar ratio. The G peak full width at half maximum for both the Ni- and Mo-C:H films increased slightly with an increase in CH4/Ar ratio, consistent with the variation in the relative integrated intensity of the D to G peak (ID/IG). Thermal annealing experiments conducted on the film samples revealed relatively stable characteristics with a minor effect on the film structure. The results showed that the impinging ion energy plays an important role in the structural properties of the Me-C:H films. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1402969
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Comparative study on the effects of ion density and ion energy on diamond-like carbon deposited by electron cyclotron resonance chemical vapor deposition (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4830-4835 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond-like carbon films were deposited using electron cyclotron resonance (ECR) chemical vapor deposition incorporated with a screen grid under different dc bias voltages to compare the effect of ion density and ion energy on the film properties. Langmuir probe measurements and optical emission spectroscopy were used to characterize the ECR plasma, while the films were characterized using Raman and infrared (IR) spectroscopies, hardness, and optical gap measurements. The plasma measurements showed that the ion density, hydrogen atom density, and CH density decreased monotonously following increase in the dc bias voltage. Raman spectra and optical gap measurements indicate the films became more graphitic with lower content of sp3-hybridized carbon atoms as the dc bias voltage was increased. An increase in hydrogen content was found in films prepared at relatively high dc bias voltage, as indicated by IR measurements. Films deposited at −150 V exhibit maximum hardness. The results show the ion density has a stronger effect on the film deposition rate and hydrogen content, while the ion energy affects the film properties more predominantly by changing the bonding structure. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1359163
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Thickness dependence of density of gap states in diamond films studied using space-charge-limited current (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5747-5753 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural and electrical characteristics of chemical vapor deposited (CVD) diamond films have been studied as a function of film thickness. The samples comprise a set of codeposited, nominally undoped diamond films with average grain size on the growth surface increasing linearly with the film thickness. Raman scattering analysis reveals a decrease of nondiamond phase and intragrain defects with increasing film thickness. Temperature dependent dc conductivity results indicate that, as the film thickness increases, the Fermi level moves towards the valence band. There is a corresponding decrease in the density of states at the Fermi level, as deduced from the space-charge-limited current in the bulk of the samples. The spatial variation in the density of states through the material closely reflects the changes observed in the structural and electrical properties of the films. Such characteristic has the implication on the application of CVD diamond in the area of electronics. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1360222
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Investigation of molybdenum-carbon films (Mo–C:H) deposited using an electron cyclotron resonance chemical vapor deposition system (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3699-3704 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have recently proposed a technique for depositing metal incorporated carbon films (Me–C:H) based on an electron cyclotron resonance chemical vapor deposition (ECR) process. This technique employs an ECR plasma derived from the excitation of source gases CH4 and Ar, together with two grids embedded within the chamber that serve as the source of the metal. It has been successfully applied for the deposition of tungsten–carbon films (W–C:H) which have been shown to exhibit a wide range of electrical, optical, and microstructural properties. These properties can be controlled through varying the deposition conditions such as the bias voltages at the grids and the substrate holder, and the flow ratio of CH4/Ar. In this work, we report on the growth and characterization of molybdenum–carbon (Mo–C:H) films deposited using the above technique incorporating two pure Mo grids. The effect of radio-frequency induced direct-current (dc) bias at the substrates was investigated. It was found that the resistivity of the films decreased by 9 orders of magnitude, and the optical gap decreased by more than 2 eV with increasing bias voltage from −38 to −130 V. The results suggest that the substrate dc bias has a crucial effect on the incorporation of Mo into the a-C:H films and the resulting microstructures, with larger bias voltages leading to an increase in the Mo fractions in the films. Concurrently, the hardness of the films was found to deteriorate from 22 to 10 GPa. The structures of these Mo–C:H films were characterized using x-ray diffraction and Raman scattering. Mo was found to exist in the forms of Mo and MoC and Mo2C. The experimental results are interpreted in terms of the effects of ion energy on the structure of the films having Mo clusters embedded within an amorphous carbon matrix. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288224
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Three-configurational surface magneto-optical Kerr effect measurement system for an ultrahigh vacuum in situ study of ultrathin magnetic films (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 3801-3805 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have constructed a three-configurational surface magneto-optical Kerr effect system, which provides the simultaneous measurements of the "polar," "longitudinal," and "transverse" Kerr hysteresis loops at the position where deposition is carried out in an ultrahigh vacuum growth chamber. The present system enables in situ three-dimensional vectorial studies of ultrathin film magnetism with a submonolayer sensitivity. We present three-configurational hysteresis loops measured during the growth of Co films on Pd(111), glass, and Pd/glass substrates. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1310346
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Modeling and analysis of hydrogen–methane plasma in electron cyclotron resonance chemical vapor deposition of diamond-like carbon (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 40-47 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Diamond-like carbon films were deposited using the electron cyclotron resonance chemical vapor deposition (ECR-CVD) system. A model for the ECR plasma was formulated using deposition parameters, such as microwave power, pressure, and hydrogen/methane ratio as inputs. Using the model, electron energy, rate constant of electron impact reactions, and density of species in the plasma are calculated. The outputs of the model are analyzed as a function of deposition conditions, such as microwave power, pressure, and hydrogen/methane ratio and compared to experimental data measured using a Langmuir probe. The results show that ion density increases following the increase in microwave power and hydrogen/methane ratio, and decreases following the increase pressure. Results from the model are in agreement with experimental data, and show that the main neutral species are H2, CH4, H, CH3, CH, C2H5, CH2, and C2H6. The main ionic species are H2+, CH4+, CH3+, CH2+, H+, CH5+, C2H4+, C2H5+, and CH+. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1421038
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Effects of microwave power on the structural and emission properties of hydrogenated amorphous silicon carbide deposited by electron cyclotron resonance chemical vapor deposition (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 2699-2705 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hydrogenated amorphous silicon carbide (a-Si1−xCx:H) films have been deposited using an electron cyclotron resonance chemical vapor deposition system. The effects of varying the microwave power from 100 to 1000 W on the deposition rate, optical band gap, film composition, and disorder were studied using various techniques such as Rutherford backscattering spectrometry, spectrophotometry, Fourier-transform infrared absorption, and Raman scattering. Samples deposited at 100 W are found to have a carbon fraction (x) of 0.49 which is close to that of stoichiometric SiC, whereas samples deposited at higher microwave powers are carbon rich with x which are nearly independent of the microwave power. The optical gaps of the films deposited at higher microwave powers were noted to be related to the strength of the C–Hn bond in the films. The photoluminescence (PL) peak emission energy and bandwidth of these films were investigated at different excitation energies (Eex) and correlated to their optical band gaps and Urbach tail widths. Using an Eex of 3.41 eV, the PL peak energy was found to range from 2.44 to 2.79 eV, with the lowest value corresponded to an intermediate microwave power of 600 W. At increasing optical gap, the PL peak energy was found to be blueshifted, accompanied by a narrowing of the bandwidth. Similar blueshift was also observed at increasing Eex, but in this case accompanied by a broadening of the bandwidth. These results can be explained using a PL model for amorphous semiconductors based on tail-to-tail states radiative recombination. A linear relation between the full width at half maximum of the PL spectra and the Urbach energy was also observed, suggesting the broadening of the band tail states as the main factor that contributes to the shape of the PL spectra observed. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1344218
    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...