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  • 1
    Electronic Resource
    Electronic Resource
    Negative persistent photoeffect on cyclotron resonance in InAs/Al0.5Ga0.5Sb quantum wells (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 667-670 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Far-infrared magneto-optical spectroscopy has been used to investigate the negative persistent photoconductivity (NPPC) effect in InAs/Al0.5Ga0.5Sb quantum wells at low temperatures. After an in situ cross-gap illumination, the electron density in the InAs well is reduced by about 28%, and the cyclotron effective mass decreases from (0.0342±0.0002)m0 to (0.0322±0.0002)m0. The time scale for the NPPC buildup transient determined from the results of a photon-dose experiment is on the order of 10 ms with an illumination power flux of ∼10 mW/cm2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357809
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of alloy composition in modulation doped AlxGa1−xAs/GaAs heterostructure (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 172-174 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have determined the alloy composition of modulation doped AlxGa1−xAs/GaAs heterostructure by Raman scattering and photoreflectance spectroscopy at room temperature. We also demonstrated that Franz-Keldysh oscillations in photoreflectance spectroscopy can be used to evaluate the band gap of semiconductor heterostructure. The band gap measured by Franz-Keldysh oscillations of photoreflectance spectrum is 1.865 eV. The alloy composition calculated from the band gap is 0.30. From the frequency positions of "GaAs-like'' and "AlAs-like'' phonon modes of the Raman scattering data, the value of the alloy composition was evaluated to be 0.29 which is in good agreement with the photoreflectance result. Both values also agree with the target composition in the molecular beam epitaxy growth and the target composition is equal to 0.30. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359364
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  • 3
    Electronic Resource
    Electronic Resource
    Two-dimensional electron gas in δ-doped double quantum wells for photodetector application (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 8112-8114 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The two-dimensional electron gas in δ-doped double quantum wells has been studied by using the Shubnikov–de Haas measurement. It was discovered that the δ-doping layer at the central barrier is able to prevent the electron coupling in the two wells and that the persistent photoconductivity can be reduced due to the thinner barrier. A δ-doped multiple quantum well structure for photodetector application was also proposed. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.365372
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of barrier material on the two-dimensional electron gas in δ-doped GaInAs-based quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 9196-9199 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed two oscillations due to the first two subbands of the two-dimensional electron gas in δ-doped AlAs0.56Sb0.44/Ga0.47In0.53As and Al0.48In0.52As/Ga0.47In0.53As quantum well by Shubnikov–de Haas measurements. From the electron densities of the two subbands we determined the energy difference between the first two subbands, ΔE01, to be 72 meV for the AlAs0.56Sb0.44/Ga0.47In0.53As, and 54 meV for the Al0.48In0.52As/Ga0.47In0.53As quantum well. By comparing with the data from an Al0.24Ga0.76As/Ga0.78In0.22As quantum well, we found that the larger band offset sample gives the higher ΔE01, but when the band offset is relatively small, the well width may determine the energy difference ΔE01. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362581
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  • 5
    Electronic Resource
    Electronic Resource
    Polymer PBT/n-GaN metal–insulator–semiconductor structure (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4589-4591 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Organic poly(p-phenylenebenzobisthiazole), PBT, is spin coated on n-GaN epilayer to serve as a gate insulating layer. The GaN is grown on c sapphire by the metalorganic-chemical-vapor-deposition method. A metal-insulator-semiconductor structure is fabricated with Al ohmic contact to the n-GaN, and Au/Al gate metal on top of the PBT. High-frequency capacitance measurements are performed. A doping concentration of 8.2×1016 cm−3 is obtained from the capacitance in the depletion region as compared with a Hall value of 7.8×1016 cm−3. Another technique of max–min capacitance method is also used in the calculation of the doping concentration. The threshold voltage is calculated as −5.1 V, and negative charges with an effective charge number density of 9.3×1011 cm−2 shift the capacitance curve towards the positive voltage side. The hysteresis phenomenon is observed and analyzed. The current–voltage curve shows a low, constant current value up to 20 V. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1429297
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of threading dislocations on electron transport in In0.24Ga0.76N/GaN multiple quantum wells (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 2167-2169 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of threading dislocations on electron transport in In0.24Ga0.76N/GaN multiple quantum wells has been studied by using transmission electron microscopy (TEM) and van der Pauw Hall effect measurements. From the cross-sectional TEM imaging, we observed the threading dislocations which "screw" through the multiple In0.24Ga0.76N/GaN quantum well. From the Hall effect measurement, we found that the Hall mobility decreases as the temperature decreases (μ∼T3/2) due to the threading dislocation scattering, and the Hall carrier concentration shows a transition from conduction-band transport to localized-state-hopping transport. The thermal activation energy of the residual donor level (probably Si) is about 20.2 meV. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123789
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  • 7
    Electronic Resource
    Electronic Resource
    Piezoelectric effect on Al0.35−δInδGa0.65N/GaN heterostructures (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2684-2686 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Al0.35−δInδGa0.65N/GaN heterostructures have been studied by using transmission electron microscopy, photoluminescence, and Shubnikov–de Haas (SdH) measurements. In the sample of δ〈0.01%, two SdH oscillations beat each other due to the population of the lowest two subbands. The carrier concentrations of these two subbands are 1.398 and 1.248×1013 cm−2 and the electric field at the interface is reduced to 2.19×104 V/cm, which is one order of magnitude smaller than that of Al0.35Ga0.65N/GaN heterostructure. We suggest that a small fraction of In atoms in the Al0.35−δInδGa0.65N can be used as a tuning parameter to control the strain and the piezoelectric field at the interface. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1469209
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  • 8
    Electronic Resource
    Electronic Resource
    Erratum: "Second subband population in δ-doped Al0.48In0.52As/Ga0.47In0.53As heterostructures'' [Appl. Phys. Lett. 66, 754 (1995)] (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 444-444 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115559
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  • 9
    Electronic Resource
    Electronic Resource
    Observation of a negative persistent photoconductivity effect in In0.25Ga0.75Sb/InAs quantum wells (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1024-1026 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have observed a negative persistent photoconductivity effect in In0.25Ga0.75Sb/InAs quantum wells with Shubnikov–de Haas measurements. The saturated reduction of the electron density in the InAs well was about 10%. The electron effective mass was found to be (0.048±0.004) m0 for an electron density of 18.0×1011 cm−2. The electron quantum lifetime decreased as the electron density was reduced by the negative persistent photoconductivity effect due to electron-hole interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112141
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  • 10
    Electronic Resource
    Electronic Resource
    Effective mass of two-dimensional electron gas in δ-doped Al0.48In0.52As/Ga0.47In0.53As quantum wells (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3355-3359 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the lowest two subbands of two-dimensional electron gas in δ-doped AlInAs/GaInAs quantum wells by Shubnikov–de Haas, quantum Hall effect, and cyclotron resonance measurements. The effective masses determined by the field-dependent cyclotron resonance measurements are 0.0576m0 and 0.0483m0 at electron densities of 17.3 and 3.6×1011 cm−2 for the first and second subbands, respectively. It was found that the electron in the first subband has heavier effective mass and shorter quantum lifetime than that in the second subband. Using the band gap of 810 meV and the band-edge mass of 0.042m0 for Ga0.47In0.53As, we calculated the average distance of the two subbands from the conduction band edge to be 150 and 61 meV, respectively. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363247
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