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  • 1990-1994  (11)
  • 1992  (11)
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  • 1990-1994  (11)
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  • 1
    Electronic Resource
    Electronic Resource
    Nonlinear spectroscopy near half-gap in bulk and quantum well GaAs/AlGaAs waveguides (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 1927-1935 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We study the nonlinear properties of bulk AlGaAs and GaAs/AlGaAs multiple quantum wells (MQW) below the half-band-gap energy using subpicosecond pulses between 1.65 and 1.7 μm. In the bulk material we find a value for the nonlinear index n2 = +3.6× 10−14 cm2/W and a two-photon absorption coefficient β = 0.26 × 10−4 cm/MW. In the MQW we measure an n2 up to 2.4 times larger, and we attribute this enhancement to a stronger 1S-exciton intermediate state. The β value is up to 25 times larger in the MQW. This larger value may result from midgap states that resonantly enhance the virtual intermediate state in two-photon absorption and act as a real transition in a two-step absorption process. The resulting figure of merit (2n2/βλ) for the bulk (MQW) material is 17 (1.6), which means that these semiconductors below half band gap are appropriate for all-optical switching and quantum optics applications. We confirm that n2 is instantaneous on the 300 fs time scale of our pulses from self-phase-modulation spectra as well as time-resolved pump-probe measurements. However, we find an intriguing exchange of energy between the two orthogonal axes as evidenced by the signal along the probe axis following the negative derivative of the pump intensity. This result may be explained by self-phase modulation of the pump combined with a low-frequency Raman process that couples the modes along orthogonal axes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351182
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  • 2
    Electronic Resource
    Electronic Resource
    Photoexcited escape probability, optical gain, and noise in quantum well infrared photodetectors (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4429-4443 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a detailed and thorough study of a wide variety of quantum well infrared photodetectors (QWIPs), which were chosen to have large differences in their optical and transport properties. Both n- and p-doped QWIPs, as well as intersubband transitions based on photoexcitation from bound-to-bound, bound-to-quasicontinuum, and bound-to-continuum quantum well states were investigated. The measurements and theoretical analysis included optical absorption, responsivity, dark current, current noise, optical gain, hot carrier mean free path, net quantum efficiency, quantum well escape probability, quantum well escape time, as well as detectivity. These results allow a better understanding of the optical and transport physics and thus a better optimization of the QWIP performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352210
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon-doped long wavelength GaAs/AlxGa1−xAs quantum well infrared photodetectors grown by organometallic vapor phase epitaxy (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 3642-3644 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report p-doped long wavelength GaAs/AlxGa1−xAs quantum well infrared photodetectors (QWIP) grown by organometallic vapor phase epitaxy. The operation of these devices is based on the photocurrent induced through valence-band intersubband absorption by holes and, unlike n-doped QWIPs, can utilize normal incidence illumination. Carbon was used as the p-type dopant in a low-pressure (30 Torr) vertical-geometry reactor. The C-doped QWIPs consisted of fifty periods of 54-nm-thick undoped AlxGa1−xAs (x=0.36 or 0.30) and C-doped GaAs wells (Lz=4 or 5 nm). Using normal incidence illumination, the C-doped QWIP with shorter wavelength response (x=0.36, Lz=4 nm) exhibited a quantum efficiency of η=21.4% and a detectivity at the peak wavelength of Dλ=5.4×109 cm (square root of)Hz/W at 77 K. The peak and cutoff wavelengths were λp=8.1 μm and λco=8.9 μm, respectively. The C-doped QWIP with longer wavelength response (x=0.30, Lz=5 nm) exhibited a normal incidence η=22.1% and D*λ=3.5×108 cm (square root of)Hz/W for λp=10.5 μm (λco=11.7 μm). The detectivity of the C-doped QWIPs is about four times less than n-doped QWIPs for the same λp but have the advantage of utilizing normal incidence illumination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350899
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  • 4
    Electronic Resource
    Electronic Resource
    Isolation properties and experimental ranges of high energy ions in GaAs and InP (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2663-2668 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The formation of high-resistivity layers in initially highly doped n- and p-type epitaxial GaAs by the passage of 25- to 50-MeV oxygen ions was investigated. The experimentally determined projected ranges of these ions are 14.0 and 28.8 μm, respectively. The sheet resistance of thin (0.5 μm) epitaxial surface layers exposed to such ions increases rapidly with fluence in the range 1013–1015 cm−2 but, depending on the initial doping density, may decrease again at higher doses. The remnant conductivity in the epitaxial layers after implantation is dominated by hopping processes with low activation energies (43–68 meV). Secondary-ion mass spectrometry was used to measure the depth profiles of Si ions implanted into GaAs and InP at energies of 30–70 MeV. The projected ranges are slightly larger (≤10%) than those predicted by current theory, and the activation efficiency of the implanted Si ions in both GaAs and InP is higher than for low-energy (∼100 keV) ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351038
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Doping of In0.53Ga0.47As and In0.52Al0.48As by Si+ and Be+ ion implantation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 215-220 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The activation kinetics and diffusion characteristics of Si+ and Be+ ions implanted into InAlAs and InGaAs were investigated for rapid thermal annealing in the temperature range 600–900 °C. The apparent activation energies for electrical activation of Be are 0.43±0.03 eV in InAlAs and 0.38±0.03 eV in InGaAs, and for Si are 0.58±0.05 eV in InAlAs and 0.64±0.06 eV in InGaAs. Higher activation efficiencies are obtained for both dopants in InGaAs relative to InAlAs and anomalously low activation for low dose Be implants is observed due to a lack of vacant sites for the Be to occupy. Extensive redistribution of Be after annealing at 750 °C, 10 s is observed in both materials, whereas Si shows no motion even for annealing at 850 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350745
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  • 6
    Electronic Resource
    Electronic Resource
    Periodic index separate confinement heterostructure InGaAs/AlGaAs multiple quantum well laser grown by organometallic vapor phase epitaxy (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 598-600 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Organometallic vapor phase epitaxy was used to grow a novel periodic index separate confinement heterostructure (PINSCH) InGaAs/AlGaAs multiple quantum well (MQW) laser. Secondary ion mass spectrometry and transmission electron microscopy were used to characterize the structure. The performance of the PINSCH laser was compared with that of a graded index separate confinement heterostructure (GRINSCH) MQW laser grown under similar conditions. The PINSCH laser uses cladding layers comprised of periodic semiconductor multilayers (Al0.4Ga0.6As/GaAs) which provide both optical and electrical confinement. Since the optical field decays over several multilayers, and therefore is far less tightly confined than in the GRINSCH structure, a significant reduction of the transverse far-field angle occurs. Comparing the performance of 5×750 μm self-aligned ridge waveguide InGaAs/AlGaAs lasers emitting at 980 nm, the PINSCH structure exhibits a transverse far-field angle of 23° compared to 46° for the GRINSCH. This is obtained at the expense of a modest increase in threshold current (19 mA vs 10 mA).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106565
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Activation and diffusion characteristics of implanted Si and Be in Al0.5In0.5P (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1117-1119 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical activation characteristics of implanted Si and Be in Al0.5In0.5P grown lattice matched to GaAs by either organometallic vapor phase epitaxy or gas-source molecular beam epitaxy were investigated as a function of ion dose (1013–1015 cm−2), annealing time (3–60 s) and annealing temperature (600–950 °C). Limiting sheet electron densities of 9×1012 cm−2 for 100 keV Si implants and sheet hole densities of 7×1012 cm−2 for 40 keV Be implants were obtained for optimum 10 s anneals at 850 or 800 °C, respectively. Co-implantation of P with Be failed to substantially improve the Be activation. Apparent activation energies for electrical activation of Si of 0.74±0.05 eV and 0.68±0.05 eV for Be were obtained from the temperature dependence of the saturated carrier density. The implanted Be displayed extensive redistribution upon annealing at 800 °C for 10 s, whereas implanted Si showed no measurable motion under any of our conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106434
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  • 8
    Electronic Resource
    Electronic Resource
    Dissociation energies of acceptor-hydrogen complexes in InP (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 1588-1590 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dissociation energies of Zn-H, Cd-H, and Mg-H complexes in p-InP have been determined from the reactivation kinetics of these passivated dopants in reverse-biased Au Schottky diodes. The reactivation process is first order under these conditions, yielding thermal dissociation energies of 1.20±0.10 eV for Zn acceptors, 1.40±0.10 eV for Cd acceptors, and 1.35±0.10 eV for Mg acceptors. These results are consistent with the model in which the hydrogen passivates the acceptor by attaching to a neighboring P atom, leaving the acceptor essentially threefold coordinated. They also indicate that acceptor-hydrogen retrapping during cool down after epitaxial growth of p-InP layers is the primary cause of apparently stable acceptor passivation seen in such layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107505
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  • 9
    Electronic Resource
    Electronic Resource
    Damage introduction in InP and InGaAs during Ar and H2 plasma exposure (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 586-588 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Changes in the sheet resistance of doped epitaxial layers of InP and In0.53Ga0.47As exposed to microwave Ar or H2 discharges were measured as a function of the exposure time (1–20 min), plasma pressure (1–20 mTorr) and the additional rf-induced negative dc bias (50–400 V) on the sample. Changes in sheet resistance of ≤10% are only obtained for low dc biases (≤−75 V) or short exposures for either type of discharge. Hydrogen plasmas led to more substantial resistance changes than argon plasmas under all conditions, with the amount of damage introduction or hydrogen passivation being strongly dependent on dc bias and exposure time, but weakly dependent on pressure. The results indicate that high density, low pressure plasmas with low dc biases are capable of causing minimal disruption to InP-based materials during dry etching for device fabrication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107845
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of gallium and arsenic precursors for GaAs carbon doping by organometallic vapor phase epitaxy using CCl4 (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 3259-3261 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The carbon doping properties of GaAs grown by low pressure (30 Torr) organometallic vapor phase epitaxy at 520–700 °C with CCl4 as the dopant precursor were compared for the four possible combinations of trimethylgallium (TMGa), triethylgallium (TEGa), arsine (AsH3), and tertiarybutylarsine (TBAs). Secondary ion mass spectrometry (SIMS), Hall measurements, and infrared absorption were used to characterize the GaAs:C layers. Very high C-doping concentrations (∼1020 cm−3) could be obtained using either TMGa or TEGa and AsH3. The use of TBAs instead of AsH3 led to a significant reduction in carbon incorporation, by approximately a factor of 5–10 per mole of As precursor over the growth temperature range examined. Hydrogen at significant concentrations (1–6×1019 cm−3) was detected by SIMS in GaAs: C layers grown at ≤550 °C utilizing all four combinations of Ga/As precursors. The existence of electrically inactive C-H complexes was confirmed by observation of the C-H stretching mode at 2635 cm−1. A post-growth anneal under helium at 550 °C for 60 s removed the C-H pairs resulting in a 50%–100% increase in hole concentration. There was no change in the hole concentration for GaAs:C grown at ≥600 °C, indicating negligible hydrogen passivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106712
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