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  • 1
    Electronic Resource
    Electronic Resource
    Quantum well thickness effect on the deep–shallow duality of Si in AlGaAs/InGaAs heterostructures (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5985-5988 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Temperature-dependent Hall measurements show that in a narrow AlxGa1−xAs/InyGa1−yAs quantum well heterostructure at low temperature, electrons trapped in Si deep levels (DX centers) are photoexcited and directly transferred to the shallow levels. When the temperature rises, these shallow-level-bound electrons are thermally ionized. On the other hand, in the wide quantum well heterostructure, the photoexcited electrons are not bound to the shallow levels even at temperatures as low as T=20 K. The relative positions between the Fermi level and the bound Si shallow level are found to be important in determining whether electrons can or cannot be trapped by the shallow levels. A simple model supports our conclusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350451
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  • 2
    Electronic Resource
    Electronic Resource
    Optical properties of quantum wells grown upon gas source molecular-beam epitaxy low-temperature buffers (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7942-7944 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs/AlGaAs quantum wells are grown on gas source molecular-beam epitaxy (GSMBE) grown low-temperature buffers (LTB). Changes in LTB growth conditions produce noticeable changes in photoluminescence (PL) intensity and linewidths of the quantum wells. Layers grown at low temperatures (200–300 °C) incorporate excess arsenic which outdiffuses during subsequent quantum well growth. Reflection high energy electron diffraction and PL results are utilized to show strain and arsenic outdiffusion from the LTBs. Excess arsenic incorporation during the growth of GaAs at low temperatures is explained in 〈m1;&10q〉terms of the association reaction of As2 to form As4 at the surface. The optimum V/〈bx〉III〈ba〉 ratio for growth of LTB by GSMBE is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.348908
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature-dependent pseudodielectric functions of GaAs determined by spectroscopic ellipsometry (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1701-1704 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the pseudodielectric functions of GaAs in the temperature range between 30 and 650 °C. Data in the spectral range of 1.24〈E〈5.00 eV was obtained by spectroscopic ellipsometry in a molecular beam epitaxy system specially designed for this purpose. All measurements were performed in situ to avoid the presence of surface adsorbates, oxides, roughness and to ensure a group V stabilized surface is maintained. A simple two-phase model could thus be used to extract the dielectric functions. Temperature dependence of the critical point energies E1, E1+Δ1, E0' and E2 are also determined. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358861
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  • 4
    Electronic Resource
    Electronic Resource
    Piezoreflectance and photoreflectance study of GaAs/AlGaAs digital alloy compositional graded structures (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 460-466 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the piezoreflectance (PzR) spectra at 300 and 80 K related to the intersubband transitions from two different (001) GaAs/AlGaAs structures, an asymmetric triangular quantum well and a rectangular quantum well, fabricated by molecular beam epitaxy using the digital alloy compositional grading (DACG) method. A comparison of the relative intensity of heavy- and light-hole related features in the PzR spectra and those in the photoreflectance emphasizes the contribution of the strain dependence of the energies of the confined states which allows us to identify the features associated with the heavy- and light-hole valence bands unambiguously. Comparison of the observed intersubband transitions with the envelope function calculations provides a self-consistent verification that the DACG method generated the desired potential profiles. Furthermore, the temperature dependence of both the energy position and broadening parameter of the fundamental conduction to heavy-hole (11H) and light-hole (11L) excitonic features are investigated in the range of 20–300 K. The anomalous behavior of the temperature dependence of the linewidth of 11H(L) excitonic features of the samples are discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360852
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of an AlGaAs/GaAs asymmetric triangular quantum well grown by a digital alloy approximation (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 4551-4556 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An asymmetric triangular quantum well was grown by molecular-beam epitaxy using a digital alloy composition grading method. A high-resolution electron micrograph (HREM), a computational model, and room-temperature photoluminescence were used to extract the spatial compositional dependence of the quantum well. The HREM micrograph intensity profile was used to determine the shape of the quantum well. A Fourier series method for solving the BenDaniel–Duke Hamiltonian [D. J. BenDaniel and C. B. Duke, Phys. Rev. 152, 683 (1966)] was then used to calculate the bound energy states within the envelope function scheme for the measured well shape. These calculations were compared to the E11h, E11l, and E22l transitions in the room-temperature photoluminescence and provided a self-consistent compositional profile for the quantum well. A comparison of energy levels with a linearly graded well is also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357013
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  • 6
    Electronic Resource
    Electronic Resource
    Optical properties of a single strained InGaAs/GaAs quantum well grown on vicinal GaAs surfaces (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 1777-1779 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the optical properties of single strained InxGa1−xAs/GaAs quantum wells (QWs) grown on GaAs substrates oriented off the (100) surface. Photoluminescence measurements indicate that QW structures grown on GaAs(100)5° toward (111)A possess superior interfaces as evidenced by the linewidth. There appears to be a decrease in the density of optically inactive traps as the angle of misorientation is increased, resulting in an enhanced optical efficiency at 77 K. However, these traps freeze out at 2 K and consequently, the optical efficiency of the various layers become independent of substrate orientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105088
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  • 7
    Electronic Resource
    Electronic Resource
    Trends of deep level electron traps in AlxGa1−xAs grown by molecular beam epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1952-1954 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Deep level transient spectroscopy is used to study one of the deep electron traps commonly seen in AlxGa1−xAs grown by molecular beam epitaxy (MBE). This trap, having the largest capture cross section of the commonly observed levels in MBE material, is measured in samples with Al composition varying from 8 to 40%. It is shown that the activation energy remains fixed with respect to the valence band, over the composition range studied. The trap is tentatively identified as a group III related vacancy. The effects of varying MBE growth parameters are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100333
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  • 8
    Electronic Resource
    Electronic Resource
    Imaging of deep level domains in semi-insulating GaAs by voltage contrast (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1152-1154 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used the voltage contrast effect to image deep level domains in semi-insulating (SI) GaAs n-i-n resistor structures. Our samples consisted of SI, undoped, liquid encapsulated Czochralski material with alloyed AuGe/Ni contacts at spacings from 1.3 to 2.27 mm. By viewing the contact side of the samples with a scanning electron microscope while the devices were biased in the oscillation region, we observed domain formation and motion from cathode to anode in real time. Long range potentials in the GaAs were observed by viewing the polished back surface of the samples. That is, the domains which are launched from the front contacts were clearly evident in voltage contrast measurements on the back of the sample. Also, because of the nonuniform charging of the semiconductor surface by the electron beam, we observed interactions between the propagating domains and the cellular dislocation structure in the SI GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98768
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  • 9
    Electronic Resource
    Electronic Resource
    Optical properties of strained asymmetric triangular InGaAs/GaAs multiple quantum wells (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2308-2310 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the first report of a strained-layer asymmetric triangular In0.15Ga0.85As/GaAs multiple quantum well structure realized by molecular beam epitaxy. Low-temperature photoluminescence experiments showed that the optical efficiency of such a structure is more than five times higher than an equivalent rectangular In0.15Ga0.85As/GaAs multiple quantum well structure grown under the same conditions. This is due to an increased collection of photoexcited carriers that are being swept by the well as a result of the field formed by compositional grading and a reduction of nonradiative recombination centers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106052
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of electroabsorption in asymmetric triangular and rectangular GaAs/AlxGa1−xAs multiple quantum wells (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 62 (1993), S. 525-527 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the first detailed experimental comparison of electroabsorption in equivalent rectangular and asymmetric triangular multiple quantum wells. The absorption spectra are extracted from reflectance and transmittance measurements on molecular beam epitaxy-grown samples. With absorption edges at the same photon energy, the asymmetric triangular quantum well is much wider than its rectangular well counterpart which reduces its absorption coefficient by approximately a factor of nine compared to the rectangular well, in agreement with theoretical estimates. Implications for electroabsorption modulator devices are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.108900
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