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  • 1
    Electronic Resource
    Electronic Resource
    Consequence of layer thickness fluctuations on superlattice miniband structures (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2641-2643 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The miniband structure of a perfect superlattice depends on the thicknesses and compositions of the constituent layers. We describe simple modeling of the consequences of fluctuations in the layer thickness. Experimental results from an asymmetric superlattice tunnel diode, where the presence of negative differential conductance reflects the existence of a miniband gap, are used to show how the sensitivity of the miniband structure to such fluctuations depends on the choice of layer thicknesses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100181
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  • 2
    Electronic Resource
    Electronic Resource
    Photoluminescence study on undoped single quantum well pseudomorphic structures (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 2158-2160 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, photoluminescence results obtained from two different undoped multilayered pseudomorphic structures grown by molecular beam epitaxy are compared. Intense and spectrally narrow emission was observed from both GaAs/InxGa1−xAs/GaAs and AlxGa1−xAs/InxGa1−xAs/GaAs structures. Excitonic emission from the quantum wells was confirmed by measurements of photoluminescence excitation spectra. The intensity and temperature dependences of the photoluminescence also revealed emission arising from bound excitons and impurities in the quantum wells. Intrinsic and extrinsic emission from confined levels was confirmed by the recorded photoluminescence excitation spectra along with intensity and temperature dependences. In the asymmetric AlxGa1−xAs/InxGa1−xAs/GaAs structure large changes were observed in the photoluminescence intensity under continuous optical excitation which are caused by the optical excitation of defects in the ternary AlxGa1−xAs on top of the pseudomorphically grown InxGa1−xAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100304
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  • 3
    Electronic Resource
    Electronic Resource
    Photoluminescence studies of free-standing quantum boxes (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3472-3480 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report photoluminescence measurements made on free-standing, lattice-matched GaAs/AlGaAs and pseudomorphic InGaAs/GaAs quantum boxes fabricated by laterally patterning quantum wells using electron-beam lithography and either reactive ion etching or ion beam milling. At temperatures below 10–20 K the luminescence efficiency of most of the GaAs quantum-box arrays tends to scale with the volume of quantum-well material remaining after processing even for the smallest boxes which have lateral dimensions of only 40–50 nm. These observations indicate that the surface recombination rate in GaAs submicron structures can be small relative to the radiative recombination rate at low temperatures. In contrast, radiative recombination in the InGaAs/GaAs quantum boxes is strongly quenched for lateral dimensions less than 500 nm. We suggest that this is because photoexcited carriers are laterally localized in the GaAs boxes by potentials of the order of a few meV, possibly associated with interface disorder or strain relaxation, and that such localization effects are smaller in the InGaAs boxes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345337
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  • 4
    Electronic Resource
    Electronic Resource
    The atomic scale structure and the electronic properties of a graded composition semiconductor layer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1603-1607 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the results of a study on the relationship between the structural and electronic properties of a graded layer of undoped AlxGa1−xAs, where x was specified to increase linearly from 0 to 0.2 over 50 nm. The layer was grown by molecular-beam epitaxy between layers of doped GaAs. A high-resolution dark-field transmission electron microscopy imaging technique of combining information from 002 and 002¯ reflections of AlxGa1−xAs allowed us to image the graded region with near atomic resolution. Differences between the predicted and measured diode performance of the graded layer are discussed in the light of our results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339946
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  • 5
    Electronic Resource
    Electronic Resource
    Sulfur doping behavior of gallium antimonide grown by molecular-beam epitaxy (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 395-399 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sulphur from an electrochemical source has been used to dope GaSb grown by molecular-beam epitaxy. The incorporation of sulphur in the epilayers has been measured by secondary ion mass spectrometry, and the effects of substrate temperature during growth and of the antimony-to-gallium flux ratio have been studied.The incorporation has been found to be a strong function of substrate temperature, varying from ∼100% below 435 °C to ∼1% at 525 °C. The incorporation also increases with antimony overpressure, varying by a factor of 3 on changing the antimony-to-gallium flux ratio from 1:1 to 4:1. The substrate temperature dependence is described by a simple kinetic model. The electrical activity of the incorporated sulphur is shown to be close to 100%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.340251
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  • 6
    Electronic Resource
    Electronic Resource
    n-type (Pb)Te doping of GaAs and AlxGa1−xSb grown by molecular-beam epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 4184-4187 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A PbTe flux has been used for n-type (Te) doping of GaAs, GaSb, and AlGaSb. The effects of surface accumulation and Te desorption were noticeable in secondary-ion mass spectroscopy profiles of GaAs layers grown at temperatures in excess of 540 °C. Te accumulation was not apparent in GaSb layers grown at temperatures up to 630 °C, but Te desorption occurred from GaSb at temperatures above 540 °C. The donor ionization energy of Te in AlxGa1−xSb is 44 meV for 0.4〈X〈0.5, i.e., significantly lower than the ionization energies of S or Se in similar material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344004
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  • 7
    Electronic Resource
    Electronic Resource
    On residual carbon acceptors in molecular-beam epitaxial GaAs (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 2673-2676 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The unintentional background concentration in molecular-beam epitaxially grown GaAs has been found to vary between 1×1014 cm−3 n type and 2×1016 cm−3 p type when grown with solid arsenic from several different suppliers. This variation is largely due to carbon incorporation which in turn is directly traceable to the arsenic charge. Increases in arsenic flux and substrate temperature both give rise to increased carbon acceptor concentrations. We propose that this carbon arises form heavy organic molecules such as rotary pump oil incorporated during the vacuum sublimation process used by some commercial suppliers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342750
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  • 8
    Electronic Resource
    Electronic Resource
    Antimony passivation of molecular-beam epitaxially grown GaAs surfaces (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1494-1496 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The use of antimony molecular beams to grow passivating films on "as-grown'' GaAs surfaces is described. The substrate need not be cooled below 350 °C for deposition as in the case of As4 and not heated above 500 °C for an extended period for removal as in the case of InAs passivation. Good electrical properties of antimony passivated, air exposed, and regrown interfaces were obtained. No degradation in macroscopic defect densities were found with this technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339931
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  • 9
    Electronic Resource
    Electronic Resource
    State-of-the-art AlGaAs alloys by antimony doping (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1300-1305 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Historically GaAlAs alloys grown by molecular-beam epitaxy have high deep level concentrations (〉1016 cm−3), low luminescent efficiency with broad peaks, and are difficult to dope controllably below mid 1016 cm−3. We report the effect that the low incident antimony molecule fluxes during growth appear to help reduce the density of deep levels below 1014 cm−3, which then allows reproducible doping control in the low 1015 cm−3 range. Exciton-dominated photoluminescence with half widths ∼4.0 meV are now routinely achieved using this technique. Further evidence for the quality improvement of AlGaAs by heavy atom (Sb) doping comes from high 4 K two-dimensional electron gas mobilities for low sheet electron densities, e.g., 1.3×106 cm2/V s for n=2×1011 cm−2. SIMS profiles of antimony content are presented and estimates of incorporated concentrations are given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337300
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  • 10
    Electronic Resource
    Electronic Resource
    Geometric and electronic structure of a semiconductor superlattice (1985)
    [s.l.] : Nature Publishing Group
    Nature 317 (1985), S. 418-419 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The superlattice3 was grown in a Vacuum Generators V8OH MBE machine, each period consisting (ideally) of 3 nm of Alo.2sGao.75As and 6 nm of GaAs. The superlattice was grown between thicker layers of heavily doped GaAs which provide ohmic contacts. Figure 1 shows a (002) dark-field electron ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/317418a0
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