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  • 1
    Electronic Resource
    Electronic Resource
    Optical characterization of GaAs pyramid microstructures formed by molecular beam epitaxial regrowth on pre-patterned substrates (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 475-480 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Arrays of GaAs pyramids with square (001) bases of length 1–5 μm have been fabricated by molecular beam epitaxy regrowth on pre-patterned GaAs (001) substrates. The optical properties of the pyramid faces have been studied by microreflection and microtransmission imaging measurements with light (λ=900–1000 nm) incident through the pyramid base. Digitized charge coupled device images indicate that total internal reflection occurs at the {110} pyramid facets and that their reflectivities are greater than 80%, provided overgrowth of the facets does not occur. These properties suggest that such structures may be suitable as the top mirror in novel micron-scale vertical microcavity devices. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1376419
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  • 2
    Electronic Resource
    Electronic Resource
    The infrared vibrational absorption spectrum of the Si–X defect present in heavily Si doped GaAs (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 137-141 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Heavily silicon doped GaAs grown by molecular beam epitaxy using a single gallium isotope source (69Ga) has been studied by infrared absorption to reveal localized vibrational modes (LVMs) of Si complexes. The structure observed close to 367 cm−1 is the same as that present in normal GaAs:Si spectra and does not result from mixed Ga isotopes. The electron trap Si–X gives three LVMs at 368.4, 370.0, and 399.6 cm−1, typical of second neighbor donor-acceptor pairs, but inconsistent with a previous proposal that its structure is the planar defect VGa–SiAs–AsGa. It is now suggested that the defect is a perturbed SiGa–VGa center, involving a second Si atom or a second vacancy. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365791
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  • 3
    Electronic Resource
    Electronic Resource
    The bonding of CAs acceptors in InxGa1−xAs grown by chemical beam epitaxy using carbon tetrabromide as the source of carbon (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6754-6760 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InxGa1−xAs layers (0≤x≤0.37) doped with carbon (〉1020 cm−3) were grown on semi-insulating GaAs substrates by chemical beam epitaxy using carbon tetrabromide (CBr4) as the dopant source. Hall measurements imply that all of the carbon was present as CAs for values of x up to 0.15. The C acceptors were passivated by exposing samples to a radio frequency hydrogen plasma for periods of up to 6 h. The nearest-neighbor bonding configurations of CAs were investigated by studying the nondegenerate antisymmetric hydrogen stretch mode (A−1 symmetry) and the symmetric XH mode (A+1 symmetry) of the H–CAs pairs using IR absorption and Raman scattering, respectively. Observed modes at 2635 and 450 cm−1 had been assigned to passivated Ga4CAs clusters. New modes at 2550 and 430 cm−1 increased in strength with increasing values of x and are assigned to passivated InGa3CAs clusters. These results were compared with ab initio local density functional theory. Modes due to AlInGaCAs clusters were detected in samples containing grown in Al and In. These results demonstrate that for InGaAs, CBr4 is an efficient C doping source since both In–CAs bonds as well as Ga–CAs bonds are formed, whereas there is no evidence for the formation of In–CAs bonds in samples doped with C derived from trimethylgallium or solid sources. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363803
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  • 4
    Electronic Resource
    Electronic Resource
    The transition from dilute aluminum δ structures to an AlAs monolayer in GaAs and a comparison with Si δ doping (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7627-7629 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superlattices of Al δ layers embedded in GaAs have been grown by molecular beam epitaxy at 400 °C on (001) GaAs. Infrared absorption measurements revealed a shift of the Al localized vibrational mode (LVM) from 361.4 to 358.3 cm−1 as the doping was increased from 0.25 monolayers (ML) to 1.4 ML per δ plane, while Raman scattering demonstrated a clear transition from the TO-like LVM to a longitudinal LO-like mode. X-ray measurements showed that the Al atoms were confined to a thickness of 6 A(ring) for the highest areal concentrations. The LVM behavior is compared with that of Si δ layers where the absorption tends to zero as the areal concentration increases up to 0.5 ML. It is concluded that SiGa atoms move off their lattice sites and/or change their charge states as the coverage approaches 0.5 ML. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357931
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  • 5
    Electronic Resource
    Electronic Resource
    The vibrational modes of silicon acceptors in p-type GaAs grown by molecular beam epitaxy on a (111)A plane (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 3574-3576 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Silicon impurities in p-type GaAs grown by molecular beam epitaxy occupy As lattice sites and give rise to an infrared active localized vibrational mode (LVM) which appears as a Fano profile near 395 cm−1 in samples with p=1019 cm−3 or 1020 cm−3. 2 MeV electron irradiation reduces p, leading to the emergence of the usual LVM absorption line of SiAs at 399 cm−1. The treatment also leads to site switching to produce SiGa donors giving an LVM at 384 cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352913
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  • 6
    Electronic Resource
    Electronic Resource
    The lattice locations of silicon atoms in delta-doped layers in GaAs (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 633-639 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used secondary ion mass spectrometry, local vibrational mode infrared absorption, and electrical characterization to study the incorporation of Si delta-doped planes in GaAs grown by molecular beam epitaxy at 400 °C, in the concentration range 0.01–0.5 monolayers. A correspondence is observed between the density of SiGa donors, the free electron concentration and the total Si coverage, up to a coverage of ∼1013 cm−2; however, above this value, the electron density falls, while [SiGa] remains constant up to a coverage of ∼1014 cm−2, and then falls below the detection limit at 0.5 monolayer coverage. These effects have been interpreted in terms of a model which takes account of Si migration and aggregation on the delta-doped plane during deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353374
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  • 7
    Electronic Resource
    Electronic Resource
    A local vibrational mode investigation of p-type Si-doped GaAs (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7839-7849 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared absorption (IR) and Raman scattering measurements have been made of the localized vibration modes (LVM) due to defects incorporating silicon impurities in p-type Si-doped GaAs grown by liquid phase epitaxy (LPE) on (001) planes and by molecular beam epitaxy (MBE) on (111)A and (311)A planes. Analysis of a closely compensated LPE sample indicated that an existing calibration factor for the SiAs LVM (399 cm−1) relating the integrated absorption coefficient (IA) to the concentration [SiAs] should be increased by 40%, so that IA=1 cm−2 corresponds to [SiAs]=7×1016 cm−3. The SiAs LVM appeared as a Fano dip in the hole absorption continuum at ∼395 cm−1 in the highly doped p-type material, some 4 cm−1 lower in frequency than its normal position in compensated GaAs. Electron irradiation of samples led to the progressive removal of the Fano dip and a shift with the emergence of the expected SiAs LVM absorption line at 399 cm−1. In MBE samples the irradiation also generated SiGa donors, but the site switching was not detected in LPE material. By contrast, Raman spectra of as-grown p-type samples exhibited a symmetrical peak at 395 cm−1, which also shifted towards 399 cm−1 as the free carriers were removed. MBE (111)A GaAs:Si compensated by SnGa donors revealed the SiAs LVM at its normal position. After hydrogenation of MBE and LPE samples, only stretch modes due to H-SiAs were observed. Passivated MBE GaAs (111)A codoped with Si and Be showed stretch modes due to both shallow acceptors. It was thereby concluded that only one type of acceptor (SiAs) was present in p-type Si-doped GaAs, contrary to previous proposals. There was no evidence for the presence of SiAs pairs or larger clusters. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357892
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  • 8
    Electronic Resource
    Electronic Resource
    Raman spectroscopic assessment of carbon-hydrogen pairs in carbon-doped GaAs layers (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 2546-2548 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman scattering by local vibrational modes of carbon-hydrogen pairs is reported for heavily carbon-doped epitaxial GaAs layers. Scattering by the longitudinal carbon mode of these pairs at 452 cm−1 shows a strong resonant enhancement for incident photon energies approaching the E1 band-gap energy of GaAs ((approximately-equal-to)3 eV). A possible mechanism for this resonance behavior is discussed in terms of the displacement of the carbon atom from its normal arsenic lattice site accompanied by a lengthening and weakening of the carbon-gallium bonds when carbon-hydrogen pairs form. The present findings demonstrate that resonant Raman scattering is an attractive tool for the detection of carbon-hydrogen pair formation in thin carbon-doped epitaxial GaAs layers grown from source materials containing hydrogen. The detection limit is estimated to be in the low 1018 cm−3 range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106908
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  • 9
    Electronic Resource
    Electronic Resource
    Reflection high-energy electron diffraction study of the GaAs:Si:GaAs system (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1805-1807 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Surface structures occurring as a function of coverage during the deposition of Si on GaAs (001) and the further changes brought about by subsequent GaAs overgrowth using molecular beam epitaxy (MBE) have been studied with reflection high-energy electron diffraction (RHEED). Deposition of Si in the presence of an As4 flux causes the surface reconstruction to change systematically from 2×4 to symmetric 3×1 via an asymmetric 3×1 stage. The process is reversed during the overgrowth of GaAs. The change in surface periodicity in the [110] direction from two-fold to three-fold is explained by a superpositioning model. The implications of this for the growth and incorporation mechanisms of Si on GaAs are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108406
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  • 10
    Electronic Resource
    Electronic Resource
    Elastic scattering and charge exchange in He^+ ion scattering from alkali metal overlayers
    Amsterdam : Elsevier
    Vacuum 38 (1988), S. 291-293 
    Details
    ISSN: 0042-207X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0042-207X(88)90063-2
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