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  • American Institute of Physics (AIP)  (23)
  • Nature Publishing Group  (14)
  • 1985-1989  (34)
  • 1955-1959  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Determination of energy-band dispersion curves in strained-layer structures (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 2227-2229 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Simultaneous measurement of both the conduction- and valence-band dispersion curves in single strained-layer structures is presented. These measurements rely on the application of recent observations regarding breaking of the usual selection rules for interband magnetoluminescence transitions in modulation-doped structures. Low-temperature magneto-luminescence data for three representative InGaAs/GaAs n-type single-strained quantum well structures are presented. For energies approaching 50 meV above the band gap, we find that the conduction band is parabolic with an effective mass of 0.071m0. Over the same energy range, the valence bands are highly nonparabolic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101367
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  • 2
    Electronic Resource
    Electronic Resource
    Critical layer thickness in In0.2Ga0.8As/GaAs single strained quantum well structures (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1004-1006 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report accurate determination of the critical layer thickness (CLT) for single strained-layer epitaxy in the InGaAs/GaAs system. Our samples were molecular beam epitaxially grown, selectively doped, single quantum well structures comprising a strained In0.2Ga0.8As layer imbedded in GaAs. We determined the CLT by two sensitive techniques: Hall-effect measurements at 77 K and photoluminescence microscopy. Both techniques indicate a CLT of about 20 nm. This value is close to that determined previously (∼15 nm) for comparable strained-layer superlattices, but considerably less than the value of ∼45 nm suggested by recent x-ray rocking-curve measurements. We show by a simple calculation that photoluminescence microscopy is more than two orders of magnitude more sensitive to dislocations than x-ray diffraction. Our results re-emphasize the necessity of using high-sensitivity techniques for accurate determination of critical layer thicknesses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98984
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  • 3
    Electronic Resource
    Electronic Resource
    Electrical and optical studies of dislocation filtering in InGaAs/GaAs strained-layer superlattices (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1098-1100 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report electrical transport and optical studies of the efficiency with which an In0.2Ga0.8As/GaAs strained-layer superlattice (SLS) can filter threading dislocations generated in a thick In0.1 Ga0.9 As layer grown on GaAs. The electrical studies, the first of their kind, rely on a novel test structure which allows electrical characterization of just the top portion of the SLS, with the bottom portion acting as the dislocation filter. For optical characterization we detect dislocations directly by photoluminescence microscopy. The electrical results show that ∼3–6 periods of filtering are needed to attain high mobilities. The photoluminescence microimages show a small density of dislocations near the top of an eight-period SLS but no dislocations for 11 or more periods. Filtering with In0.2Ga0.8As/GaAs SLS's is more effective than with GaAs0.8P0.2/GaAs SLS's, possibly because of larger interlayer differences in strain and elastic constants for the former.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100032
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  • 4
    Electronic Resource
    Electronic Resource
    Controversy of critical layer thickness for InGaAs/GaAs strained-layer epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 377-379 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The critical layer thickness for InxGa1−xAs layers in InxGa1−xAs/GaAs single strained quantum wells (SSQW's) and strained-layer superlattices (SLS's) are investigated. Photoluminescence microscopy (PLM) images and x-ray rocking curves for two series of SSQW and SLS structures corresponding to many different layer thicknesses were obtained. We find that the PLM technique, which directly images dislocations and is sensitive to low dislocation densities, is much more suitable for determining the onset of dislocation creation. The x-ray technique can detect lattice relaxation by dislocations but only at relatively high densities of dislocations. Using the former technique, we determine critical thicknesses of 190 A(ring) for SSQW's and 250 A(ring) for SLS's with x≈0.2. These results are near the theoretical predictions of J. W. Matthews, S. Mader, and T. B. Light [J. Appl. Phys. 41, 3800 (1970)] (150 and 300 A(ring), respectively) and are much lower than results obtained by x-ray or other techniques which sense lattice relaxation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99471
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  • 5
    Electronic Resource
    Electronic Resource
    Band-edge alignment in heterostructures (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1877-1878 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conduction-band and valence-band energies are presented for ternary III-V compounds in a novel way. These data are used to evaluate new material combinations for heterostructure devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102158
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  • 6
    Electronic Resource
    Electronic Resource
    High photoconductive gain in lateral InAsSb strained-layer superlattice infrared detectors (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1961-1963 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Both large photoconductive gain and long wavelength photoresponse were observed in lateral photodetectors constructed from type II, InAsSb, strained-layer superlattices. In a novel, four-layer superlattice, gain values as large as 90 are reported with a long wavelength cutoff of 8.7 μm at 77 K. The gain is sensitive to the structure and composition of the superlattice, and the sweepout of minority carriers is eliminated with the appropriate contacts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100336
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  • 7
    Electronic Resource
    Electronic Resource
    GaAs/(In,Ga)As, p-channel, multiple strained quantum well field-effect transistors with high transconductance and high peak saturated drain current (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 52 (1988), S. 975-977 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaAs/In0.2 Ga0.8 As structures with two paralleled 10 nm quantum wells, modulation doped from the top, bottom, and middle with Be, have been fabricated into multiple strained quantum well field-effect transistors (MQWFET's) with 1×150 μm2 Ti/Au gates and examined both illuminated and in the dark at 300 and 77 K. Measurements on van der Pauw structures fabricated simultaneously with the transistors showed hole mobilities and sheet carrier densities to be 200, 3100, and 8040 cm2/V s, and 5.7×1012, 1.8×1012, and 1.5×1012 cm−2 , at 300, 77, and 4 K, respectively. Shubnikov–de Haas measurements made below 4 K verified the existence of a double-channel two-dimensional hole gas with a strain-shifted light-hole ground state in the quantum wells with an effective hole mass of 0.15 me . A representative p-channel MQWFET showed well-saturated common-source output characteristics, both illuminated and unilluminated, at all measurement temperatures. Measured peak extrinsic transconductances and peak saturated drain currents for the unilluminated 1 μm device were 31 and 60 mS/mm and 27 and 67 mA/mm, at 300 and 77 K, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99246
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  • 8
    Electronic Resource
    Electronic Resource
    Role of experimental resolution in measurements of critical layer thickness for strained-layer epitaxy (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1080-1082 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental measurements of critical layer thicknesses (CLT's) in strained-layer epitaxy are considered. Finite experimental resolution can have a major effect on measured CLT's and can easily lead to spurious results. The theoretical approach to critical layer thicknesses of J. W. Matthews [J. Vac. Sci. Technol. 12, 126 (1975)] has been modified in a straightforward way to predict the apparent critical thickness for an experiment with finite resolution in lattice parameter. The theory has also been modified to account for the general empirical result that fewer misfit dislocations are generated than predicted by equilibrium calculation. The resulting expression is fit to recent x-ray diffraction data on InGaAs/GaAs and SiGe/Si. The results suggest that CLT's in these systems may not be significantly larger than predicted by equilibrium theory, in agreement with high-resolution measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.98746
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  • 9
    Electronic Resource
    Electronic Resource
    Electric field response of a semiconductor superlattice optical mirror from electroreflectance spectra (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1324-1326 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report low-field electroreflectance (ER) spectra of an all-semiconductor multilayer optical mirror structure. The structure, consisting of alternating blocks of AlAs/Al0.5Ga0.5 As and Al0.5Ga0.5As/GaAs multiple quantum well layers, was grown by molecular beam epitaxy without wafer rotation. Thickness variations across the wafer produce a position-dependent reflectance spectrum. The observed line shape of the band-edge exciton depends on its wavelength position relative to the mirror spectrum and cannot be explained by ordinary ER theory, due to the rapidly varying background mirror reflectance. Computer simulations, using the matrix method to calculate the reflectance for different layer thicknesses and exciton energies, agree qualitatively with the data. A strong enhancement in ER response is predicted near the minima in the mirror spectrum. This enhancement is important in electo-optic reflectance modulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101644
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  • 10
    Electronic Resource
    Electronic Resource
    Energy levels of finite-depth quantum wells in an electric field (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 2273-2276 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Numerical calculations of energy levels and wavefunctions for a particle in a finite quantum well subject to an electric field are described. The calculations are restricted to the regime where the tunneling rate out of the well is small. In this regime the results are in good agreement with results of an approximate calculation wherein the finite well is replaced by an infinitely deep well whose width has been adjusted (separately for each level) to obtain the correct zero-field eigenvalue, as recently proposed for the ground state by Miller et al. [D. A. B. Miller, D. S. Chemla, T. C. Damen, A. C. Gossard, W. Wiegmann, T. H. Wood, and C. A. Burrus, Phys. Rev. B 32, 1043 (1985)]. Over a significant range of well depths and fields (which are the only variables, provided that appropriately normalized units are used), it is found that the difference between the approximate and exact eigenvalues can be accurately estimated from a simple empirical formula. These results should be useful in studies of electro-optic effects in semiconductor quantum-well structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337989
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