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  • 11
    Electronic Resource
    Electronic Resource
    Enhancement of electrical and structural properties of GaN layers grown on vicinal-cut, a-plane sapphire substrates (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 608-610 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of significant enhancement in the electrical and crystalline properties of GaN layers grown on vicinally cut, a-plane sapphire substrates. Room-temperature Hall mobility and x-ray rocking curve data show a nearly twofold improvement, independent of the processing conditions, for layers grown on substrates having vicinal angles of 1.5° compared to on-axis substrates. Transmission electron microscopy shows reduced edge dislocation density and better alignment of the grains in layers grown on vicinally cut substrates. Preliminary photoluminescence measurements also indicate pronounced differences in the yellow band spectra between the on-axis and off-axis cut substrates. These findings contrast the relatively modest improvements observed in layers grown on c-plane substrates with vicinal angles as high as 10°.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121871
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  • 12
    Electronic Resource
    Electronic Resource
    B implants in Si1−xGex/Si (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 391-393 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Boron ion implantations were performed into 100 nm thick, undoped, strained Si1−xGex alloy films with x values of 0, 0.1, and 0.2 grown on (100) Si. B implants of 1×1013, 1×1014, and 1×1015 cm−2 were done at 20 keV. Implant activation was accomplished by using either 20 s rapid thermal anneals or 10 min furnace anneals, both at temperatures up to 800 °C. The annealed material was characterized by Hall, secondary ion mass spectrometry, and x-ray rocking curve measurements. We observed an increasing B activation with increasing Ge concentration in the alloy. For x=0.2 we obtained 100% B activation for 1×1013 and 1×1014 cm−2 implants annealed at 700 and 800 °C. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116695
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  • 13
    Electronic Resource
    Electronic Resource
    Thermal stress-induced, high-strain fragmentation of buried SiGe layers grown on Si (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2678-2680 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Buried Si1−xGex layers grown on Si at elevated temperatures of 700 to 800 °C generally exhibit x-ray rocking curves which are significantly broader than those predicted for perfect crystals, suggesting that the layers are strain-relieved. However, calculations using these rocking curves show the materials to be either nearly- or fully-strained. The source of x-ray broadening accompanied by high strain is found to be an abrupt, thermally-induced fragmentation of the layer into small, slightly misoriented regions during the cool-down, such that the as-grown strain remains unchanged. The fragments are typically rectangles a few micrometers wide, with well-defined boundaries along [110]-type directions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114290
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  • 14
    Electronic Resource
    Electronic Resource
    Dependence of InAs phonon energy on misfit-induced strain (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 3434-3436 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transverse-optical (TO) phonon energy in strained InAs quantum wells has been investigated by using far-infrared absorption. We observe that the TO phonon energy decreases when the misfit-induced biaxial tension in the InAs single quantum well is increased. Our result shows a stronger phonon energy dependence on the strain than the one reported by Cerdeira et al. [Phys. Rev. B 5, 580 (1972)]. The discrepancy may be explained by stress relaxation near the surface in their experiment. The application of our result will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110137
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  • 15
    Electronic Resource
    Electronic Resource
    Accurate determination of effective quantum well thickness: Infrared absorption by transverse-optical phonons (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 583-585 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied far infrared transmission spectra of various AlSb/InAs/AlSb single quantum wells, where the well width ranges from 60 to 200 A(ring). Because the quantum well is thin, the far infrared absorption due to transverse-optical phonons is not saturated. We obtained excellent fitting to the transmission spectra by taking into account the complex dielectric functions with a transfer matrix formalism. The thickness of InAs quantum wells can be determined with monolayer resolution. High-resolution transmission electron microscopy shows clear lattice images in a region away from the AlSb/InAs interfaces. The thickness of the pure nonintermixed InAs region is in excellent agreement with our far infrared absorption results. Phonon absorption can therefore provide a nondestructive method to effectively determine the number of pure InAs monolayers, in spite of interdiffusion occurring at the interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107844
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  • 16
    Electronic Resource
    Electronic Resource
    X-ray rocking curve measurement of composition and strain in Si-Ge buffer layers grown on Si substrates (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 825-827 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The level of strain and the fraction of Ge in SiGe layers grown on Si can be found rapidly and unambiguously using double-crystal x-ray diffraction and a simple application of the linear elasticity theory combined with Vegard's law. The method gives excellent results for 0.4-μm-thick buffer layers of SiGe/Si containing 5%–50% germanium. It is shown that lattice relaxation rises abruptly at x(Ge)≥15%, and that some strain remains for x(Ge) as high as 50%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104501
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  • 17
    Electronic Resource
    Electronic Resource
    Implantation damage in GaAs-AlAs superlattices of different layer thickness (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1338-1340 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report that two GaAs-AlAs superlattices of different layer thickness show dramatically different crystal damage when ion irradiated under identical conditions. The samples, held at 77 K, were implanted with 100 keV 28Si at doses of 3×1013 cm−2 to 1×1015 cm−2. Ion channeling results show amorphization threshold doses of 1×1015 cm−2 for the 7.0 nm GaAs-8.5 nm AlAs superlattice and 4×1014 cm−2 for the 3.5 nm GaAs-5.0 nm AlAs superlattice. At low doses, the shorter period superlattice was more robust, with no damage peak observed in ion channeling spectra for doses as high as 1×1014 cm−2. For a dose of 7×1013 cm−2, double crystal x-ray diffraction measurements show a 6 arcsec broadening of the (004) peak, relative to that of the unimplanted sample, for both superlattices. However, only the finer period superlattice exhibits a broadening (10 arcsec) of the (224) diffracted peak indicating a distortion in an additional direction. A mechanism involving the formation of slightly misaligned crystal domains is suggested to describe the behavior of the finer period superlattice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105493
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  • 18
    Electronic Resource
    Electronic Resource
    Fabrication of GaAs and InAs wires in nanochannel glass (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2846-2848 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A newly developed porous glass, nanochannel glass, was used to fabricate uniform, high-density GaAs and InAs micro- and nanowires with high aspect ratios. The fabrication process utilized reactions between organogallium and organoindium compounds with arsine to produce polycrystalline GaAs and InAs with crystallite sizes of approximately 50–130 A(ring) when annealed at 400–500 °C. At the higher annealing temperatures, the InAs wires exhibited an increase in surface porosity and grain size, whereas the GaAs wires maintained a uniform, smooth texture. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117338
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  • 19
    Electronic Resource
    Electronic Resource
    Detection of simultaneous lattice expansion and contraction in low-energy, H-implanted InP (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 825-826 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the observation of simultaneous lattice expansion and contraction in InP implanted with low-energy protons, using the high-resolution x-ray rocking-curve technique. For implantation with 260 keV, 1×1016 protons/cm2, the volume of the crystal extending from the surface to approximately 1.6 μm deep is contracted with a mean effective strain of −7×10−5, while the proton containing region is expanded to a maximum positive strain of about 7×10−4. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113434
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  • 20
    Electronic Resource
    Electronic Resource
    Solid-phase regrowth of amorphous GaAs grown by low-temperature molecular-beam epitaxy (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 320-321 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have shown that solid-phase recrystallization of an amorphous GaAs film can form a single-crystal film. We observed the phenomenon in GaAs, deposited by molecular-beam epitaxy at a growth temperature (Tg) of 190 °C and annealed at 775 or 850 °C. Observations in the transmission electron microscope indicate that annealing brings about a lower degree of As precipitation in the as-grown amorphous films (Tg〈215 °C) than in the as-grown single-crystal films (340 °C(approximately-greater-than)Tg(approximately-greater-than)215 °C). The lower degree of As precipitation in the initially amorphous material appears to insure a high concentration of As donors rather than a high concentration of resistivity increasing As precipitates. Electrical measurements show that the low-range (Tg〈215 °C) annealed sample has an extremely high n-type carrier concentration (1018 cm−3) and mobility (800 cm2 V−1 s−1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110057
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