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  • 11
    Electronic Resource
    Electronic Resource
    Photo-Hall studies of high-purity GaAs (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 7425-7433 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-purity GaAs layers which are nearly or fully depleted of carriers at low temperatures, due to surface and interface depletion effects, can be characterized electrically by utilizing the phenomenon of persistent photoconductivity. To facilitate electrical measurements of such layers, at 4.2 K the sample is momentarily illuminated by above band-gap light, which causes a reduction in the surface and interface depletion region. After illumination the effects of the photoinduced charge neutral region persist until at some higher temperature, the charge distribution in the sample relaxes back to its original equilibrium state. Results of variable temperature Hall-effect measurements performed under these conditions show that the sheet carrier concentration is increased as compared to measurements obtained in the dark but that the mobility is unchanged. The increase in the sheet carrier concentration after illumination results from the decrease of the surface and interface depletion widths. Such measurements can provide a method for judging the quality of layers that are fully depleted of carriers. The mobility of a high-purity GaAs layer which becomes fully depleted of carriers at low temperatures in the dark, measures 180 000 cm2/V s at 77 K by this method. Photocapacitance-voltage profiling measurements clearly show the change in the depletion widths. A model is presented which accurately depicts the temperature dependence of the band-bending potentials at the surface and interface after illumination with above band-gap light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349738
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  • 12
    Electronic Resource
    Electronic Resource
    Measurements of deep levels in high-purity molecular beam epitaxial GaAs (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5287-5289 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Constant capacitance deep-level transient spectroscopy measurements are performed on molecular beam epitaxially grown GaAs layers with net carrier concentrations of 3.3–6.5×1014 cm−3. Four trap levels are detected, three of which are usually detected in molecular beam epitaxial layers, and the fourth, a very shallow trap at 30 meV, has not been previously reported. Determination of the concentrations for this new level dispute the accepted interpretation of Hall measurements near and above room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334843
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  • 13
    Electronic Resource
    Electronic Resource
    Red shifting the intersubband response of quantum-well infrared photodetectors by thermal annealing (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4737-4740 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Selectively red shifting the photoresponse of intersubband GaAs/Al0.25Ga0.75As multiple-quantum-well (MQW) infrared photodetectors (QWIPs) by furnace and rapid thermal annealing is explored. Selective interdiffusion of the MQW is achieved by dielectric encapsulating (SiO2 or Si3N4) the surface. The high dark current of annealed QWIPs is attributed to dopant out-diffusion from the QWs into the barriers. Declining responsivities result from reduced carrier density in the QW and a red shift of the intersubband transition energy. In this work, the intersubband energy is determined by the Fourier synthesis model and compared with experimental results (further confirming the interdiffusion mechanism). Minimal dark current and responsivity degradation is observed for Si3N4-encapsulated QWIPs red shifted by 1 μm © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363456
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  • 14
    Electronic Resource
    Electronic Resource
    Carbon incorporation in InP grown by metalorganic chemical vapor deposition and application to InP/InGaAs heterojunction bipolar transistors (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4233-4236 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The incorporation of residual carbon has been studied for InP grown at low temperatures using TMIn and PH3 by low-pressure metalorganic chemical vapor deposition. n-type conduction is observed with electron concentrations as high as 1×1018 cm−3, and the electrical activation efficiency is 5%–15%. Carbon incorporation is found to be highly dependent on substrate temperature, suggesting that the rate-limiting step is desorption of CHy (0≤y≤3) from the surface during growth. Hydrogen is also incorporated in the layers during growth. The electron mobilities are lower for C-doped InP than for Si-doped InP. InP/InGaAs heterojunction bipolar transistors with C as the p-type base dopant and either Si or C as the n-type emitter dopant have been fabricated and compared. Devices with a carbon-doped base and emitter showed degraded performance, likely as a result of deep levels incorporated during growth of the emitter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356011
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  • 15
    Electronic Resource
    Electronic Resource
    Characterization of ion-implanted InxGa1−xAs/GaAs 0.25 μm gate metal semiconductor field-effect transistors with Ft(approximately-greater-than)100 GHz (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2690-2691 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This work presents millimeter wave performance achieved by ion-implanted InGaAs/GaAs metal semiconductor field-effect transistor devices. A current gain cutoff frequency ft of 126 GHz and maximum frequency of oscillation fmax of 232 GHz have been measured for 0.20 μm gate length devices. The ft and low-field Hall mobility data, measured at 300 and 112 K, lead us to conclude that the average electron velocity under the gate is mainly due to the high-field velocity rather than low-field electron mobility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104809
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  • 16
    Electronic Resource
    Electronic Resource
    Instability of partially disordered carbon-doped AlGaAs/GaAs superlattices (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2910-2912 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Superlattices of Al0.3Ga0.7As/GaAs grown by metalorganic chemical vapor deposition and heavily doped with carbon using CCl4 were annealed for 24 h at 825 °C under a variety of ambient and surface encapsulation conditions. Pronounced changes in photoluminescence from the annealed superlattices with storage time at room temperature, as opposed to an excellent reproducibility of that from the as-grown, not annealed samples, are reported. These changes may be indicative of degraded thermal stability of the annealed superlattice crystals due to high-temperature-induced lattice defects. The systematic failure to fabricate buried-heterostructure quantum well lasers via impurity-induced layer disordering in similarly doped AlGaAs/GaAs crystals, which may be related to the same effect, is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103750
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  • 17
    Electronic Resource
    Electronic Resource
    Surface Fermi-level changes in n-type GaAs determined from Hall-effect measurements (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2934-2936 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Changes in the surface Fermi-level position in n-type epitaxial GaAs samples are determined by Hall-effect measurements of the corresponding changes in the sheet concentrations and theoretical calculations of the surface depletion thickness. The changes are induced and reversed repeatedly by alternating wet chemical treatments in hydrogen peroxide and ammonium hydroxide. This is the first known use of hydrogen peroxide to restore the surface Fermi level to near its starting value and demonstrate the repeated variation of the surface Fermi level by ammonium hydroxide. The results agree with the predictions of the advanced unified defect model and with published reports of increased band bending on n-type material, rather than with conflicting reports of decreased band bending. The results also indicate that problems may exist with other techniques used to measure surface- potential changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103735
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  • 18
    Electronic Resource
    Electronic Resource
    Precipitate formation in carbon-doped base of InGaP/GaAs heterojunction bipolar transistors grown by low-pressure metal organic chemical vapor deposition (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2993-2995 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of intermediate temperature annealing on the carbon-doped base region of InGaP/GaAs heterojunction bipolar transistors (HBTs) was studied. This work shows that after annealing at only 600 °C a sample doped at 5.5×1019 cm−3 displays carbon precipitation. InGaP/GaAs HBT structures were grown for the annealing study. Hall measurements were used to measure hole concentration. Atomic force microscopy was employed to identify carbon precipitation. The annealing process not only removes hydrogen from the base but also creates carbon precipitates. The dc current gain measurements imply that the carbon precipitates increase base recombination. These results are very important in the growth and postgrowth annealing of high gain HBTs. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123990
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  • 19
    Electronic Resource
    Electronic Resource
    Residual acceptor impurities in undoped high-purity InP grown by metalorganic chemical vapor deposition (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 752-754 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Zn and an unidentified acceptor species, labeled A1, are the only residual acceptors that have been observed in a wide variety of undoped high-purity InP samples grown by metalorganic chemical vapor deposition. Carbon is not incorporated at detectable concentrations as a residual acceptor in metalorganic chemical vapor deposited InP. However, the longitudinal and transverse optical phonon replicas of the free-exciton recombination occur at the same energy as the donor/conduction band-to-acceptor peaks for C acceptors in low-temperature photoluminescence spectra. Since these replicas are usually present in photoluminescence spectra measured under moderate or high optical excitation, care must be exercised so that these peaks are not misinterpreted as C-related transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102702
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  • 20
    Electronic Resource
    Electronic Resource
    Carbon-doped base GaAs/AlGaAs heterojunction bipolar transistor grown by metalorganic chemical vapor deposition using carbon tetrachloride as a dopant source (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 361-363 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon tetrachloride (CCl4) has been used as a carbon doping source for the base region of a GaAs/AlGaAs Npn heterojunction bipolar transistor (HBT) grown by low-pressure metalorganic chemical vapor deposition (MOCVD). Transistors were fabricated and characterized for dc current gain, emitter-base junction ideality factor, base contact resistance, and external base resistance. Microwave characterization by S-parameter measurement was performed to determine the common emitter current gain and maximum available gain as a function of frequency. Transistors with the base contact area self-aligned to a 3×10 μm emitter finger had a dc current gain as high as 50, an emitter-base junction ideality factor of n=1.2, and a current gain cutoff frequency of ft=26 GHz. Transistors of equal emitter area without self-alignment exhibited dc current gain as high as 86, n=1.2, and ft=20 GHz. A base contact resistance of Rc=2.85×10−6 Ω cm2 and an external base sheet resistance of Rs=533.4 Ω/(D'Alembertian) were measured. These preliminary results indicate that carbon doping from CCl4 may be an attractive substitute for Zn or Mg in GaAs/AlGaAs HBT structures grown by MOCVD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102785
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