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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 4288-4294 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Zn-doped, p-type, Ga0.85In0.15As samples grown by low-pressure metalorganic vapor phase epitaxy, with free carrier concentrations in the range of 3.22×1015–1.95×1020 cm−3, have been studied by photoluminescence as a function of temperature. At low doping levels, recombinations involving discrete impurity states and free excitons provided a measurement of both the 0 K reference band gap, Eg(0)=(1.296±0.003) eV, and of the Zn acceptor binding energy, E(Zn0)=(25±3) meV in the Ga0.85In0.15As alloy. High doping concentrations cause a band gap shrinkage ||ΔEg|| which has been observed with photoluminescence experiments. A model taking into account Kane band tails and assuming a constant matrix element for the relevant optical transitions has been fitted to the photoluminescence spectra of layers with doping levels in the range of 1.6×1019–1.95×1020 cm−3. This provided a good description of the experimental results. The 0 K band gap shrinkage, which appeared to be smaller than in GaAs, follows the relation ||ΔEg||=1.4×10−8p1/3 for Ga0.85In0.15As, with ||ΔEg|| in eV and p in cm−3.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 7836-7843 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present here a detailed study of photomodulated transmission and reflectivity at room and liquid-nitrogen temperatures of a series of InxGa1−xAs/GaAs superlattices and a single quantum well. Our samples span a variety of alloy compositions and quantum-well widths. We compare the results of our measurements with the predictions of an envelope-function calculation, which includes wave-vector dependence of the minibands. This comparison allows identification of several spectral features unmistakably arising from miniband dispersion. Also, accurate determination is made of the band-offset parameter, whose value is discussed in the context of those obtained by other authors.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2321-2327 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Anisotropic optical, electrical, and structural properties have been observed in thick InxGa1−xAs/GaAs single heterostructures grown by low-pressure metal-organic vapor phase epitaxy on (001) and slightly misoriented GaAs substrates. The luminescence of the (001) samples is polarized and the electron mobility is higher along one of the 〈110〉 directions. Asymmetric distributions of surface ridges and misfit dislocations have been observed in secondary electron micrographs (SEMS) of the surfaces and in transmission electron micrographs. Strong anisotropy and a clear correlation between the anisotropic optical, electrical, and structural properties have been observed for samples grown on (001) oriented substrates. For (001) samples, the results indicate that the anisotropic properties are induced by nonuniform strain relaxation. For samples grown on misoriented substrates, SEM and micro-Raman spectroscopy indicate a better crystal quality. The anisotropic properties are found to be reversed and the degree of anisotropy is significantly reduced. The results suggest the improvement of interfacial coherency owing to the mechanism of nucleation on a substrate presenting a series of steps and ledges. The reduction of defects within the epilayer can be partly due to a faster strain relief in vicinal (001) epilayers.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4033-4039 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Several multiquantum wells of InP/GaxIn1−xAsyP1−y grown by chemical-beam epitaxy have been studied by high-resolution x-ray diffraction, low-temperature photoluminescence, and Raman scattering to characterize interfacial layers between the barriers and the wells. These interfacial layers are created during the initial stage of growth of the quaternary material as a result of the longer transient for the saturation of the group-III elements flux. The combination of x-ray diffraction and photoluminescence allows a precise determination of the interfacial layer thickness and composition grading and shows that interface roughness is of the order of 1 monolayer. Raman scattering confirms these results and is used to determine values of the sound velocity and of the index of refraction in the quaternary alloy material.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 2633-2639 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Low temperature photoluminescence measurements of GaxIn1−xAsyP1−y alloys nearly lattice matched to InP to study the line broadening of the observed band to band and near band gap transitions in these materials were performed. We find that the dominant broadening mechanism is alloy broadening that originates from the spatial fluctuations of the band gap energy due to random anion and cation distribution. A model that assumes that occupation of the group-III sites by Ga and In atoms and of the group-V sites by As and P atoms occurs randomly, is fitted to the photoluminescence spectra of our samples. This provides an excellent description of the experimental results.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 2640-2648 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have carried out a detailed structural and optical characterization of Ga0.47In0.53As/InP multiple quantum wells grown by chemical beam epitaxy using a well-defined sequence of growth interruption times between successive layers. These growth interruption times result in the formation of interfacial layers which drastically alter the structural properties of Ga0.47In0.53As/InP multiple quantum wells. An analysis of double-crystal x-ray diffraction data reveals that exposure of InP to arsine for 2 s is sufficient to create approximately 3 monolayers of InAs0.55P0.45 ternary under biaxial compressive strain at the InP/Ga047In0.53As interface. Moreover, exposure of Ga0.47In0.53As to phosphine for 2 s results in the formation of approximately 2 monolayers of Ga0.48In0.52As0.21P0.79 quaternary under biaxial tensile strain at the Ga0.47In0.53As/InP interface. We find that long exposures to hydrides (over 5 s) rather than short ones give rise to interfacial layers with less compositional disorder and/or thickness fluctuation. Moreover, photoluminescence and absorption spectroscopy data reveal the negligible effect of InAsxP1−x and GaxIn1−xAsyP1−y interfacial layers on the emission and optical absorption properties of Ga0.47In0.53As/InP multiple quantum wells with sufficiently thick Ga0.47In0.53As layers. © 1996 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1488-1491 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Etching of a chemical-beam-epitaxy-grown InP/InGaAs multilayer structure with reactive ion etching (RIE) and laser-assisted dry etching ablation (LADEA) is carried out in order to evaluate the extent of the damage induced by these two etching methods. Micro-Raman spectroscopy indicates a systematic broadening of the phonon lines as a function of depth of a RIE fabricated crater. In contrast, LADEA which is based on the application of an excimer laser for the removal of the products of chemical reaction, shows no measurable changes in the phonon line widths when compared to as-grown material. The results suggest that LADEA has potential for the photoresistless fabrication of damage free microstructures. © 1995 American Institute of Physics.
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  • 8
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High purity InP layers have been grown by chemical beam epitaxy using H2 as the carrier gas for transporting the metal alkyl trimethylindium into the growth chamber. InP layers exhibiting Hall mobility as high as 238 000 cm2/V s at 77 K and with a peak value of 311 000 cm2/V s at 50 K and residual Hall concentration of 6×1013 cm−3 at 77 K were grown at 500 °C using a low V/III ratio (2.2) and a phosphine (PH3) cracking cell temperature of 950 °C. The 4.2 K photoluminescence spectra were dominated by donor bound exciton (D0,X)n up to n=6 and free exciton (X) transitions for InP layers grown above 500 °C. All the InP samples exhibited very weak acceptor related photoluminescence transitions indicating very low concentration of acceptors. The energy of these transitions suggests that Mg is the major residual acceptor. Donor impurity identification by high resolution magnetophotoluminescence indicated that S and Si are the major impurities. PH3 has been found to be the major source of S impurities in the present study.
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 82 (1997), S. 4883-4888 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InP was grown by chemical beam epitaxy in narrow windows of widths varying between 20 and 2 μm, oriented along the [011] or [01¯1] directions opened in a SiO2 mask on an (001) InP substrate. Several facets appear along the sidewalls and on the edge of the mesas owing to different growth rates on different crystallographic planes. These can be understood as consequences of the migration of group III species from one crystallographic plane to another. We have studied the formation of such facets and their effects on the growth of GaInAs/InP structures of various thicknesses. The samples were studied using a field emission scanning electron microscope (SEM) and low temperature photoluminescence (PL). SEM micrographs show that for lines oriented along the [011] direction the dominant InP sidewall facets are (111)B planes on which GaInAs does not grow as long as Ga and In species can migrate towards (001). For the orthogonal direction, however, the lateral growth rate of the InP sidewalls is large and the faceting of the mesas is more complicated. The PL spectra of GaInAs quantum wells grown on such mesas exhibit several peaks whose energy depends on the initial width of the mask. They can be interpreted in terms of crystallographic plane dependent migration and desorption rates of Ga and In species. The (111)B facets of [011] directed mesas were used to produce inverted V-shaped mesa wire structures. © 1997 American Institute of Physics.
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1062-1064 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photovoltaic spectra of InGaAs/GaAs multiple quantum wells grown by metalorganic vapor phase epitaxy show several well defined spectral structures which are interpreted in terms of the sample characteristics. Results obtained by this relatively simple method are comparable to data obtained by other optical techniques on the same material, and in good agreement with calculations taking into account the strain-induced splitting and the coupling between the wells.
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