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  • 1
    Electronic Resource
    Electronic Resource
    Study of ErAs/GaAs strained-layer structures using optical absorption and ion channeling (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 2176-2180 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystal-field splittings recently observed in the Er-related optical absorption spectra of ErAs films grown on GaAs by molecular-beam epitaxy are further investigated with respect to their applicability in characterizing strain accommodation in ErAs/GaAs multilayer structures. Rutherford backscattering axial channeling measurements are used to directly assess strain accommodation in the epitaxial films. The crystal-field splittings observed in room-temperature absorption spectra of samples containing thick strain-relieved ErAs layers are consistent with the cubic (Oh) symmetry expected for the Er lattice site in unstrained ErAs. In sharp contrast, a multilayer structure containing two-monolayer-thick, coherently strained ErAs layers shows pronounced changes in the energies, linewidths, and relative intensities of the crystal-field-split spectral lines, as well as the appearance of additional weak absorption lines. This behavior is attributed to strain-induced distortion of the crystal field in which the rare-earth ions reside. The relative influence of hydrostatic and uniaxial strain components on the optical spectra is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346545
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of the interface bond type on the far-infrared reflectivity of InAs/GaSb superlattices (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5642-5644 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have investigated the far-infrared reflectivity spectra of two series of InAs/GaSb superlattices grown with GaAs- or InSb-like interfaces. Significant differences in the spectra induced by the interface bond type can be observed. The theoretical simulation of the experimental data allowed us to accurately determine the energy of the interface TO phonons and the actual thickness of the region in which they are localized. The inactivity of the InAs TO phonon vibration at the interface can be explained by modeling a nonhomogeneous strain accommodation across the heterointerfaces. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359689
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  • 3
    Electronic Resource
    Electronic Resource
    Crystal-field splittings of Er3+(4f11) in molecular beam epitaxially grown ErAs/GaAs (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 34-36 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed infrared-spectroscopic study is presented of the intra 4f-shell transitions 4I15/2→4I13/2 of Er3+(4f11), at λ=1.54 μm, in single-crystal ErAs films deposited on GaAs substrates by molecular beam epitaxy. Using Fourier-transform infrared absorption spectroscopy crystal-field splittings of both the 4I15/2 ground state and the first electronically excited state 4I13/2 are observed. Good agreement is found between the measured transition energies and those calculated for 4f11 ions in a crystal field of cubic (Oh) symmetry, as expected for the Er lattice site in unstrained ErAs. From the infrared absorption data, the relevant cubic fourth and sixth-order crystal field parameters are determined spectroscopically for the first time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105569
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  • 4
    Electronic Resource
    Electronic Resource
    High performance InAs/Ga1-xInxSb superlattice infrared photodiodes (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 3251-3253 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The optical and electrical properties of infrared photodiodes diodes based on InAs/(GaIn)Sb superlattices grown by molecular beam epitaxy were investigated. The diodes, with a cut-off wavelength around 8 μm show a current responsivity of 2 A/W. By proper adjustment of the p-doping level above the n-background concentration the depletion width exceeds a critical size of about 60 nm, leading to the suppression of band-to-band tunneling currents. Above that critical width the dynamic impedance R0A at 77 K reaches values above 1 kΩ cm2 leading to a Johnson-noise-limited detectivity in excess of 1×1012 cm(square root of)Hz/W. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120551
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  • 5
    Electronic Resource
    Electronic Resource
    Resolved structure in the quenching band of the EL2 center in GaAs, studied by infrared spectroscopy (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 2115-2117 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Infrared measurements at low temperature on undoped semi-insulating GaAs reveal additional details in the photoresponse of the EL2 center. In the continuous spectral recording of the optical cross section for the bleaching of the EL2 absorption the zero phonon line (ZPL) at 1.039 eV and six phonon replicas with 11 meV separation have been observed. A modified Huang Rhys calculation is necessary to reproduce both the relative intensity of the ZPL and the maximum of the broad band at 1.17 eV. Using the intensity of the resolved structure for calibration, we calculate the contribution of the intracenter transition to the total EL2 absorption spectrum. Comparison with the known time constants for photoionization and quenching yields a probability of (1.2±0.3)% for transformation to the metastable state after intracenter excitation. The ZPL in the absorption spectrum shows considerable broadening and a decrease in energy by 3 meV in the temperature range 10–65 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98964
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  • 6
    Electronic Resource
    Electronic Resource
    Infrared studies of the dynamics of transformations between normal and metastable state of the EL2 center in GaAs (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 679-681 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The bleaching of the EL2 absorption and its thermal regeneration are typical time-dependent processes. Compared to the conventional time transient analysis, faster and more accurate data acquisition is described. This technique is based on the combined use of optical absorption and its time derivative, measured while either the energy of the bleaching light or the sample temperature is varied. The peak of the spectral response for bleaching shifts to lower energies in the temperature range 10 to 130 K. The activation energy for thermal regeneration can decrease by a factor of 6 between semi-insulating and n-type samples. We report the first optical identification of persistent electrons, which are photogenerated during EL2 bleaching at 10 K. The thermal disappearance of persistent electrons and holes has also been studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98332
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  • 7
    Electronic Resource
    Electronic Resource
    Spectroscopic ellipsometry for characterization of InAs/Ga1−xInxSb superlattices (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5452-5457 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The pseudodielectric function of InAs/Ga1−xInxSb superlattices (SLs) grown by solid-source molecular-beam epitaxy, was measured by spectroscopic ellipsometry (SE) for photon energies ranging from 1.2 to 5 eV. The width of the extrema in the SL pseudodielectric function derived from the E1 and E1+Δ1 interband transitions of the SL constituents InAs and Ga1−xInxSb, was found to depend on the structural quality of the SL. Differences in the SL quality caused by different sequences of InSb- like and GaAs-like interfaces, were easily detected by SE. The formation of the intended interface alternations was verified by Raman spectroscopy. The extrema in the SL pseudodielectric function originating from the E1 and E1+Δ1 interband transitions of Ga1−xInxSb were found to shift to lower energies with increasing In content x. Finally SE has been applied to the analysis of a complete InAs/Ga1−xInxSb SL detector structure. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367376
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  • 8
    Electronic Resource
    Electronic Resource
    Infrared spectra and electron spin resonance of vanadium deep level impurities in silicon carbide (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 1184-1186 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Trace impurities of vanadium in Lely-grown silicon carbide single crystals have been detected by their strong, polytype-specific photoluminescence in the 1.3–1.5 μm near-infrared spectral range, as well as by infrared absorption. The spectra arise from the intra-3d-shell transitions 2E(3d1)→2T2(3d1) of V4+Si(3d1). Electron spin resonance reveals that VSi in SiC acts as a deep acceptor, V4+Si(3d1)/V3+Si(3d2)−ˆA0/A−, and possibly also as a deep donor. The role of vanadium as minority-carrier lifetime killer in SiC-based optoelectronic devices is suggested from these data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102555
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  • 9
    Electronic Resource
    Electronic Resource
    Hydrogen induced vibrational and electronic transitions in chemical vapor deposited diamond, identified by isotopic substitution (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 177-179 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Homoepitaxial diamond films grown by chemical vapor deposition from 12C and 13C containing gases have been studied by Fourier transform infrared spectroscopy. A sharp absorption band observed at 3123 cm−1 is attributed to a CH vibrational absorption. It resembles the previously observed 3107 cm−1 absorption band in natural diamond. Isotopic replacement of carbon, hydrogen, and nitrogen by 13C, 2H, and 15N reveals, that a CH center without nitrogen participation is responsible for this new absorption. Furthermore, new hydrogen related electronic transitions have been observed around 7300 cm−1. These lines shift to higher energies in 13C crystals, in accordance with the increase of the electronic band gap. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113126
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  • 10
    Electronic Resource
    Electronic Resource
    Space-charge effects in photovoltaic double barrier quantum well infrared detectors (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 782-784 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We show that the spatial distribution of the dopants strongly influences the transport asymmetry and the photovoltage observed in double barrier quantum well intersubband photodetectors. This influence can be quantitatively explained by the local space-charge fields arising from an asymmetry of the doping profile with respect to the well centers. The resulting transport model correctly predicts both the observed transport asymmetry of the photocurrent and the opposite asymmetry of the dark current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.109906
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