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  • 1
    Electronic Resource
    Electronic Resource
    Influence of In on Si local vibrational modes in InxGa1−xAs (0≤x≤0.12) (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7797-7804 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Local vibrational modes (LVM) of Si in substitutional sites have been observed by resonant Raman spectroscopy in highly doped (≥8×1018 cm−3) InxGa1−xAs layers, either relaxed or under strain, on [100] GaAs substrates. The peak frequency ωLVM of the Si on Ga site (SiGa) LVM in unstrained samples shifts to lower values with increasing In content. For x≤0.10 this shift is clearly higher than expected from a linear interpolation between the measured values in the binaries. The comparison between the SiGa peak frequency measured in both a full strained layer and a relaxed layer with similar composition provides a rough determination of the deformation potentials for the SiGaLVM in these layers: q/ω2LVM=−2.7±1 and p/ω2LVM=−2.5±1. As the In content becomes higher the width of the SiGa peak increases much more than that of the GaAs-like longitudinal optical-phonon peak, revealing the splitting due to the loss of local symmetry introduced by the In. New calibration factors for the Si-defect concentrations have been deduced, which allow estimation of the solubility limit for the Si incorporation in substitutional positions, which ranges from 2.3×1019 to 2.6×1019 cm−3 for the layers at the growth conditions used. The analysis of the integrated intensity of the LVM Raman peaks indicates that the degree of electrical compensation is clearly reduced for increasing In up to x≤0.05, due to both an increase of the solubility limit for Si in these layers and a saturation or slight reduction of the SiAs-related defect concentrations. This conclusion is also supported by Hall and plasmon measurements. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358521
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  • 2
    Electronic Resource
    Electronic Resource
    A Raman spectroscopic study of the Si, Be, and C incorporation in InxGa1−xAs relaxed layers (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4690-4695 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The incorporation of high concentrations ((approximately-greater-than)1019 cm−3) of Si, Be, and C in InxGa1−xAs relaxed layers has been studied as a function of In content (x≤0.16) by Raman spectroscopy of local vibrational modes (LVM). The frequencies of the Raman peaks resulting from the convolution of several split modes shift to lower values as the In content is increased, the carbon acceptor (CAs) local mode frequency showing the strongest dependency on x. Features attributed exclusively to the influence of In on second-neighbor sites are identified only in the Si-doped samples. The transverse and longitudinal modes expected from the splitting of a LVM of CAs with one In first neighbor are not observed in layers with x up to 0.085. A new calibration for the BeGa, CAs, and Si-related LVM leads to the conclusion that In increases the total electrical activation of Si and favors its incorporation on group-III sublattice sites. In contrast, no influence of In on the Be or C doping activation has been detected. The analysis of the CAs LVM spectra supports the view that in InxGa1−xAs CAs is preferably surrounded by Ga instead of In atoms for x≤0.085. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359816
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  • 3
    Electronic Resource
    Electronic Resource
    High-quality Si-implanted In0.53Ga0.47As epitaxial layers and their application to n+p junction devices (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3478-3482 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Si implantations into undoped In0.53Ga0.47As have been carried out to obtain n-layers suitable for device applications. Different doses and energies have been analyzed. After rapid thermal annealing at 850–875 °C for 10–20 s, electrical activations of about 100%, and mobilities as high as 4000 cm2/V s were obtained. Different Hall measurements show that there is no redistribution of the dopants. Photoluminescence measurements demonstrate the satisfactory recrystallization of the lattice and the excellent activation of the dopants. Electrical characteristics of n+p junctions made by Si implantation into Zn-doped In0.53Ga0.47As are described. Junction behavior at forward bias could be explained by recombination in the space-charge zone mechanisms, whereas different tunneling processes dominate at reverse bias. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372369
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis and modeling of AlxGa1−xN-based Schottky barrier photodiodes (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 2081-2091 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Schottky barrier photovoltaic detectors have been fabricated on n-AlxGa1−xN(0≤x≤0.35) and p-GaN epitaxial layers grown on sapphire. Their characteristics have been analyzed and modeled, in order to determine the physical mechanisms that limit their performance. The influence of material properties on device parameters is discussed. Our analysis considers front and back illumination and distinguishes between devices fabricated on ideal high-quality material and state-of-the-art heteroepitaxial AlxGa1−xN. In the former case, low doping levels are advisable to achieve high responsivity and a sharp spectral cutoff. The epitaxial layer should be thin (〈0.5 μm) to optimize the ultraviolet/visible contrast. In present devices fabricated on heteroepitaxial AlxGa1−xN, the responsivity is limited by the diffusion length. In this case, thick AlxGa1−xN layers are advisable, because the reduction in the dislocation density results in lower leakage currents, larger diffusion length, and higher responsivity. In order to improve bandwidth and responsivity, and to achieve good ohmic contacts, a moderate n-type doping level (∼1018 cm−3) is recommended. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1305838
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  • 5
    Electronic Resource
    Electronic Resource
    High visible rejection AlGaN photodetectors on Si(111) substrates (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2785-2787 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the fabrication and characterization of Schottky barrier photodetectors based on Si-doped Al0.35Ga0.65N layers grown on Si(111) substrates, for solar UV-band monitoring (λ〈320 nm). The epilayers have been obtained by plasma-assisted molecular-beam epitaxy, showing a full width at half maximum of 15 arcmin in x-ray diffraction measurements. A very high visible rejection (〉104) and a responsivity of 5 mA/W at 257 nm are reached. The detector time response is limited by the resistance×capacitance product, with a minimum time constant of 20 ns in the zero-load-resistance limit. After photodiode voltage breakdown, the effect on the detector response is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126475
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  • 6
    Electronic Resource
    Electronic Resource
    Resonant-cavity InGaN multiple-quantum-well green light-emitting diode grown by molecular-beam epitaxy (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2198-2200 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A resonant-cavity InGaN/GaN multiple-quantum-well (MQW) light-emitting diode, incorporating a semitransparent Bragg reflector, has been grown by molecular-beam epitaxy. A 30% reflectivity AlGaN/GaN distributed Bragg reflector and a Ni coating were used as bottom and top mirrors, for backside emission. High-resolution x-ray diffraction data reveal high-quality interfaces in both the MQW and the Bragg mirror. Room-temperature electroluminescence is centered at 507 nm, with an estimated output power of 5 μW at 20 mA. The external efficiency is increased by a factor of 12 compared to similar structures without resonant cavity. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1463701
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  • 7
    Electronic Resource
    Electronic Resource
    High-quality distributed Bragg reflectors based on AlxGa1−xN/GaN multilayers grown by molecular-beam epitaxy (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2136-2138 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Distributed Bragg reflectors based on AlxGa1−xN/GaN multilayer stacks have been grown by plasma-assisted molecular-beam epitaxy on GaN templates. The nominal Al composition ranged from 30% to 45%, and the layer thicknesses of the ten-period stack were designed for a target wavelength of 510 nm. Transmission electron microscopy data reveal periodic structures where (Al,Ga)N on the GaN interface is sharper than GaN on the (Al,Ga)N one. X-ray diffraction spectra fitted to a dynamic diffraction simulation model yield an estimate of the layer thicknesses, Al%, and lattice strain. Reflectivity values above 50% at 510 nm have been reproducibly achieved, in very good agreement with the results of the matrix-method simulation. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1401090
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  • 8
    Electronic Resource
    Electronic Resource
    AlGaN metal–semiconductor–metal photodiodes (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3401-3403 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the fabrication and characterization of AlGaN metal–semiconductor–metal photodiodes with sharp cutoff wavelengths from 365 to 310 nm. The detectors are visible blind, with an ultraviolet/visible contrast of about 4 orders of magnitude. The photocurrent scales linearly with optical power for photon energies both over and below the band gap, supporting the absence of photoconductive gain related to space-charge regions. No persistent photoconductivity effects have been detected. Time response is limited by the RC product of the measurement system, the transit time of the device being far below 10 ns. The normalized noise equivalent power at 28 V bias is lower than 17 pW/Hz1/2 in GaN detectors, and about 24 pW/Hz1/2 in Al0.25Ga0.75N photodiodes. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123358
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  • 9
    Electronic Resource
    Electronic Resource
    AlxGa1−xN:Si Schottky barrier photodiodes with fast response and high detectivity (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2146-2148 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gold and nickel Schottky barrier photovoltaic detectors have been fabricated on Si-doped AlxGa1−xN layers (0≤x≤0.22) grown on sapphire by metalorganic vapor phase epitaxy. Responsivity is independent of the Schottky metal or diode size, and also of the incident power in the range measured (10 mW/m2–2 kW/m2). A higher visible rejection has been observed in the spectral response of Au photodiodes (〉103). Time response is resistance-capacitance limited, with time constants as short as 14 ns in Al0.22Ga0.78N diodes. Low frequency noise studies are also presented, and detectivities of 6.1×107 and 1.2×107 mHz1/2 W−1 are determined in GaN/Au and Al0.22Ga0.78N/Au detectors, at −2 V bias. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122405
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  • 10
    Electronic Resource
    Electronic Resource
    Strong localization in InGaN layers with high In content grown by molecular-beam epitaxy (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 231-233 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of the III/V ratio and growth temperature on the In incorporation has been studied in thick (〉300 nm) InGaN layers, with In mole fractions from 19% to 37%, grown by molecular-beam epitaxy on sapphire and on GaN templates. Significant desorption of In occurs at growth temperatures above 550 °C. Symmetric and asymmetric reflections from high resolution X-ray diffraction reveals that the layers are not fully relaxed. A bowing parameter of 3.6 eV is calculated from optical absorption data, once corrected for strain-free band gap values. The increase of both, the absorption band-edge broadening and the photoluminescence full width at half maximum at room temperature with the In content, is discussed in terms of a strong In localization effect. This localization effect is further evidenced by the S-shaped temperature dependence of the emission energy. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1432751
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