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  • Electronic Resource  (47)
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  • Electronic Resource  (47)
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  • 1
    Electronic Resource
    Electronic Resource
    Identification of a nonradiative recombination center in GaAs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4449-4451 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on the identification of the CuGa acceptor level as a recombination center in GaAs. Using time-resolved photoluminescence (PL) we have studied the recombination of excess charge carriers in metalorganic vapor-phase epitaxy GaAs/AlGaAs double heterostructures. The recombination in one particular set of samples was clearly nonradiative and the trap level derived from our measurements coincides with that of CuGa as seen in the PL spectra. The temperature dependence of the capture coefficients is consistent with a multiphonon process and allows for the determination of the coupling strength for electron and hole capture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352184
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  • 2
    Electronic Resource
    Electronic Resource
    Linewidth enhancement factor and carrier-induced differential index in InGaAs separate confinement multi-quantum-well lasers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 2467-2469 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Quantum-well lasers can achieve a low spectral linewidth because of their high differential gain, leading to a lower linewidth enhancement factor α than for bulk lasers. The differential refractive index and the gain of InGaAs separate confinement multi-quantum-well lasers with two different quaternary barrier layers, have been determined from the spontaneous emission spectra below threshold. The measured value of the α factor is about 2.8 up to 3.5 at the gain maximum for both laser structures. The refractive index and the gain spectra are connected via the Kramers–Kronig relation. Therefore, the differential refractive index and the α factor have been deduced from calculated gain spectra with an additional contribution of the intraband transitions of the free carriers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349402
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  • 3
    Electronic Resource
    Electronic Resource
    Indirect-band-gap transition in strained GaInAs/InP quantum-well structures (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5067-5071 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Using photoluminescence (PL) and time-resolved measurements, the valence-band structure of tensile strained GaInAs quantum wells has been evaluated. From temperature-dependent PL, LO-phonon-assisted transitions at energies of about 32 meV below the band gap transition were observed. In addition, a hundredfold increase in the carrier lifetime of tensile strained quantum wells compared to unstrained layers was measured. Both findings are strong indications that the maximum of the valence band in k space is shifted away from the center of the Brillouin zone in tensile strained quantum wells near a critical composition, where the lowest heavy-hole and light-hole levels cross each other, thus giving rise for indirect optical transitions as predicted by theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355749
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  • 4
    Electronic Resource
    Electronic Resource
    Nonlinear optical absorption in separate confinement multi-quantum-well structures due to spatial band bending (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 1184-1186 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on nonlinear optical absorption in InGaAs/InGaAsP separate confinement multiple-quantum-well (SCMQW) structures based on charge-carrier induced band bending. Carrier induced localization and related changes in absorption strength due to spatial separation of electrons and holes are utilized to design SCMQW structures with a new type of optical nonlinearity. Experimentally, we observe strong changes in optical absorption with increasing excitation power. Compared to exciton bleaching, the new nonlinearity dominates at low carrier densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358464
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  • 5
    Electronic Resource
    Electronic Resource
    Intra- and interwell transitions in GaInN/GaN multiple quantum wells with built-in piezoelectric fields (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 82-84 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied optical transitions in GaInN/GaN single and multiple quantum wells using time-resolved photoluminescence spectroscopy. Our results show that the energy positions of the dominant emission lines strongly depend both on the well width and on the number of wells. In the case of multiple quantum wells, time-resolved measurements clearly distinguish multiple emission lines. These observations are consistently explained by considering the large built-in piezoelectric field in strained GaInN quantum wells. The multiple emission lines are attributed to intra- and interwell transitions between nearest and next-nearest neighbors. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122958
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  • 6
    Electronic Resource
    Electronic Resource
    Hole transport over heterobarriers in InP based multiple quantum well structures (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 1323-1325 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a systematic analysis of the hole transport over heterobarriers in the InGaAs(P)/InP material system. The experiments have been performed on our recently developed all-optical switching structures [C. Knorr et al., Appl. Phys. Lett. 69, 4212 (1996)], which offer an elegant access to hole transport rates. We have varied barrier thickness, barrier height, bias voltage, and temperature. The time constants vary from 30 μs to 30 ns. Our model calculations, including all heavy and light hole subbands, show that only thermally assisted tunneling can explain both the temperature and electric field dependence of the transport rates. We have extracted the activation energies. The hole capture time is determined as 250±50 fs. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120982
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  • 7
    Electronic Resource
    Electronic Resource
    Single variant ordering in GaInAs/InP (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 2127-2129 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Spontaneously ordered Ga0.47In0.53As grown on substrates with the (001) surface tilted 4° towards {111}B are studied using spectroscopic methods as well as x-ray diffraction, transmission electron diffraction and dark-field transmission electron microscopy. The single variant ordering is proved by the absence of one class of the ordering induced 〈fraction SHAPE="CASE"〉12{111}B superlattice spots in transmission electron diffraction patterns as well as by the tilted polarization of the photoluminescence emerging from the samples cleaved edge. The temperature dependence of the luminescence peak position shows an anomalous behavior at low temperatures and a strong dependence of the peak position on the excitation power. From low temperature absorption measurements, we find a band gap reduction of 37 meV and a valence band splitting of 13.2 meV. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119357
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  • 8
    Electronic Resource
    Electronic Resource
    A mechanism for low-power all-optical switching in multiple-quantum-well structures (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 4212-4214 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate a novel type of optical switching mechanism in pin separate confinement multiple quantum well (SCMQW) structures. By introducing additional large barriers into conventional InGaAs(P)/InP SCMQW structures, the transport of photogenerated holes can be controlled in such a way that they accumulate in the intrinsic region. This positive space charge leads to a local screening of the internal field in the optical confinement layer and to an enhancement of the internal field in the MQW region. We characterize the optical nonlinearity, which is based on the quantum confined Stark effect (QCSE), experimentally and theoretically. As the nonlinearity is observed at input powers 〈1 W/cm2 in the basic nonoptimized structures presented here, we propose to use our structure especially for low-power optical switches. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116989
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of carrier transport/capture and gain flattening in picosecond pulse generation of InGaAs microcavity lasers (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3137-3139 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have fabricated and studied the dynamics of In0.16Ga0.84As λ-cavity lasers focusing on the influence of carrier transport/capture and gain flattening by using optical resonant pumping and off-resonant pumping. With the off-resonant pumping, shoulders in the lasing pulse shape were observed, while no shoulder appeared with the on-resonant pumping. From rate equation analysis and time-resolved photoluminescence measurement, it was concluded that the shoulders result from carrier transport/capture effects. Saturation of the inverse rise time was observed at high pump levels. This results from gain flattening due to the steplike density of states of 2D carriers. The pulse width obtained from the laser was as narrow as 7.7 ps. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116807
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  • 10
    Electronic Resource
    Electronic Resource
    Optical gain in GaInN/GaN heterostructures (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3746-3748 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By optical gain spectroscopy we have studied the fundamental laser properties of GaInN/GaN heterostructures grown on sapphire. Utilizing the stripe excitation method we have measured optical gain spectra at room temperature. Due to the low symmetry of the wurtzite structure and the resulting splitting of the uppermost valence bands, we find optical gain only for the TE mode. Our analysis shows that the optical gain is due to direct band-to-band transitions in an electron-hole plasma. For gain amplitudes typically found in lasers, we find carrier densities up to 3×1019 cm−3, which are likely to lead to rather large threshold current densities. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115993
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