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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of InP/GaAs/Si structures grown by atmospheric pressure metalorganic chemical vapor deposition (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1083-1088 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The thickness dependence of material quality of InP-GaAs-Si structures grown by atmospheric pressure metalorganic chemical vapor deposition was investigated. The InP thickness was varied from 1–4 μm, and that of the GaAs from 0.1–4 μm. For a given thickness of InP, its ion channeling yield and x-ray peak width were essentially independent of the GaAs layer thickness. The InP x-ray peak widths were typically 400–440 arcsec for 4-μm-thick layers grown on GaAs. The GaAs x-ray widths in turn varied from 320–1000 arcsec for layer thicknesses from 0.1–4 μm. Cross-sectional transmission electron microscopy showed high defect densities at both the InP-GaAs and GaAs-Si interfaces. In 4-μm-thick InP layers the average threading dislocation density was in the range (3–8)×108 cm−2 with a stacking fault density within the range (0.4–2)×108 cm2. The He+ ion channeling yield near the InP surface was similar to that of bulk InP (χmin∼4%), but rose rapidly toward the InP-GaAs heterointerface where it was typically around 50% for 1-μm-thick InP layers. All samples showed room-temperature luminescence, while at 4.4 K, exciton-related transitions, whose intensity was a function of the InP thickness, were observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343043
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamical x-ray rocking curve simulations of nonuniform InGaAs and InGaAsP using Abeles' matrix method (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1364-1368 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Computer simulations of the intrinsic (400) reflecting power of In1−xGaxAs layers having graded compositions are presented. We find that multiple x-ray peaks can result from a linearly graded region which implies that an interpretation which ascribes individual peaks to sublayers having a constant lattice parameter may not always be correct. We find that, in general, the simulations are asymmetric and that they have a full width at half maximum less than ∼100 arcsec. We have simulated an actual rocking curve of a single In1−xGaxAs1−yPy layer grown on a (100) InP substrate by vapor-phase epitaxy which exhibited multiple peaks, and we find that a good fit is possible if the layer had a graded lattice parameter. Comparing dynamical to kinematical simulations for a 3-μm-thick linearly graded layer, we find that most of the features resulting from the grading can be explained using kinematical theory. However, only the dynamical simulations can properly account for the reflecting power in the vicinity of the substrate peak and for the lack of fine structure which is observed in the absence of a discontinuity in Bragg spacing at the layer/substrate interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337311
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  • 3
    Electronic Resource
    Electronic Resource
    Erratum: "X-ray and Raman characterization of AlSb/GaSb strained layer superlattices and quasiperiodic Fibonacci lattices'' [J. Appl. Phys. 64, 6733 (1988)] (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 3963-3963 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344504
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  • 4
    Electronic Resource
    Electronic Resource
    Erratum: "Misfit stress in InGaAs/InP heteroepitaxial structures grown by vapor-phase epitaxy'' [J. Appl. Phys. 57, 249 (1985)] (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1238-1238 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337803
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  • 5
    Electronic Resource
    Electronic Resource
    Critical layer thickness and strain relaxation measurements in GaSb(001)/AlSb structures (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1687-1694 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of critical layer thicknesses and strain relaxation have been made for AlSb single layers and GaSb/AlSb superlattices on GaSb(001) using ion scattering/particle-induced x-ray techniques, x-ray diffraction, and Raman scattering. The ion beam techniques and x-ray diffraction indicate a critical thickness on the order of 100–170 A(ring). Raman scattering from superlattice samples using 5145 A(ring) excitation shows the most rapid strain relaxation versus layer thickness and indicates a lower apparent critical thickness on the order of 50–100 A(ring). The influence of the finite experimental resolution is addressed. The experimental critical thickness and the strain relief are compared to theoretical models. The equilibrium critical thickness of these models is consistent with the experimental value, indicating that metastable strain retention is not a dominant process in the GaSb(100)/AlSb system under the present growth conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.344387
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  • 6
    Electronic Resource
    Electronic Resource
    Lattice-mismatch-generated dislocation structures and their confinement using superlattices in heteroepitaxial GaAs/InP and InP/GaAs grown by chemical beam epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 520-530 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report a detailed transmission electron microscopy and x-ray double-crystal diffractometry study of the lattice-mismatch-induced defect structures in InP grown on (100) GaAs substrate and vice versa by chemical beam epitaxy. A rough estimate of the dislocation densities in GaAs on InP is 2×1010 cm−2 at the interface and 5×107 cm−2 at the surface of the epilayer. The corresponding values in InP on GaAs are slightly lower as expected for the compressive stress state for InP. The majority of the dislocations lie on the {111} slip planes with 1/2 [110]- and 1/2 [101]-type Burgers vectors. A cross-grid-type interfacial misfit dislocation array is not observed. Instead, a complicated dislocation structure near the interface, consisting of overlapping pyramidal dislocation tangles (PDT) similar to those observed previously in InGaAs on InP caused by interfacial misfit particles, is presented. The interfacial dislocations form a cellular structure in GaAs on InP and a random structure in InP on GaAs. A Moiré fringe spacing study of InP on GaAs indicates a localized change in composition at the interface, possibly due to As incorporation or GaAs/InP intermixing. The formation of PDT defects and the variation in composition at the interface suggest a breakdown of layer-by-layer growth in the initial stage of growth which results in island nucleation. A dislocation mechanism for the PDT formation is also proposed. All epilayers prepared by chemical beam epitaxy (CBE) without two-stage growth are specular. X-ray rocking curve linewidth measurement shows a general reduction in the linewidth with increasing growth temperature and is insensitive to the substrate misorientation. Fine surface morphology revealed by Nomarski interference microscopy shows no correlation with x-ray linewidth. Results on the reduction of dislocation by varying growth temperature, substrate misorientation angle, and using AlGaAs/GaAs superlattice barriers for dislocation propagation are presented and their effectiveness are discussed. A realistic scheme to achieve an unwarped wafer with low dislocation density is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343568
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  • 7
    Electronic Resource
    Electronic Resource
    Semi-insulating properties of Fe-doped InP grown by hydride vapor phase epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 5880-5884 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial layers grown by hydride vapor phase epitaxy using N2 as a carrier gas were studied. Charge transport measurements at temperatures as high as 416 K and as low as 38 K were made on layers grown on (100)-, (311)B-, (511)B-, and (110)- oriented substrates. Resistivities in the range 4×106–2×1010 Ω cm were obtained in all cases except for growth on (311)B surfaces. In that case resistivities were in the range 1×103–5×107 Ω cm. Detailed fitting to I-V data was done using a two trap model, and a good fit was obtained if traps lying at 0.68 and 0.30 eV below the conduction band were included. The deeper lying trap concentration which gave the best fit was in the range 1–8×1015 cm−3. This level corresponds to the Fe3+(arrow-right-and-left)Fe2+ transition which is usually observed in semi-insulating bulk and MOCVD grown Fe-doped InP and which compensates the background donors. A concentration lying in the range 2–20×1018 cm−3 must be used for the 0.30-eV trap to produce a good fit. The presence of this trap at such a large concentration also explains our observations that the Fermi level moves up in the band gap as the temperature is decreased. We speculate that this trap is N impurity related. Secondary-ion-mass spectrometry results rule out the possibility that the 0.30-eV trap is Fe related. Low-temperature photoluminescence spectra typical of Fe-doped InP were obtained and revealed a broad band at 1.1 eV. Such a band has been commonly reported for bulk InP:Fe and is usually assigned to an Fe related deep level. Our results suggest that this assignment may not be correct for our material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343611
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  • 8
    Electronic Resource
    Electronic Resource
    Substrate rotation-induced composition modulation in epitaxial AlGaAs grown by molecular-beam epitaxy (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 3838-3844 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We observe a periodic variation of Al mole fraction along the growth direction in AlGaAs grown by molecular-beam epitaxy on GaAs substrate by cross-sectional transmission electron microscopy (TEM). The wavelength of such composition modulation in AlGaAs is inversely proportional to the substrate rotation speed during growth and is independent of the growth temperature used. Uniform composition along the growth direction is achieved by increasing the rotation speed such that the modulation period merges into a continuum composition. The minimum change in the Al mole fraction required to obtain a visible periodic contrast in the [200] dark-field TEM images is estimated semiempirically to be about 6% in Al0.3Ga0.7As. Composition modulation was not observed in Al0.7Ga0.3As, indicating an improvement in the uniformity of the Al-beam flux profile across the wafer at a high source temperature. Although Hall measurements and high-resolution x-ray diffractometry did not show any difference in layers grown with and without composition modulation, both the photoluminescence intensity and its uniformity across the wafer improved considerably in Al0.3Ga0.7As with increasing rotation speed from 5 to 16 rpm. A deep donor-acceptor recombination with an activation energy around 157 meV was observed in Si-doped Al0.36Ga0.64As.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343370
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  • 9
    Electronic Resource
    Electronic Resource
    X-ray and Raman characterization of AlSb/GaSb strained layer superlattices and quasiperiodic Fibonacci lattices (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 6733-6745 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Double-crystal rocking curves of samples grown on (001)-oriented GaSb substrates by molecular-beam epitaxy have been analyzed by fitting computer simulations to data for the symmetric (004) and (002) reflections and for asymmetric (115) reflections. Rocking curves revealed a multiplicity of superlattice diffraction peaks. Dynamical diffraction theory using Abeles matrix method [D. W. Berreman, Phys. Rev. B 14, 4313 (1976)] was applied for the symmetrical reflections. We compare our results to standard kinematical simulations, and we find that there are significant differences. For the asymmetric reflections a new dynamical computer simulation code [D. W. Berreman and A. T. Macrander, Phys. Rev. B 37, 6030 (1988)] involving an 8×8 matrix solution of Maxwell's equations was used. Lattice incoherency was determined from measurements of the in-plane mismatch. Dramatic diffraction peak broadening was observed for incoherent superlattices, and this broadening was attributed to a mosaic structure formed by misfit dislocations. Peak broadening was used to infer both a growth direction as well as an in-plane coherence length. The in-plane coherence length was found to be somewhat less than the mean distance between misfit dislocation lines. Mosaic broadening of diffraction peaks of a quasiperiodic lattice was found to be qualitatively similar to that observed for the periodic superlattices. Raman measurements of zone-folded acoustic phonon spectra yielded superlattice periods that agreed with the x-ray measurements within a few percent. Analysis of Raman peak intensities to yield individual layer widths was not found to be quantitative within the confines of current analytic models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342005
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  • 10
    Electronic Resource
    Electronic Resource
    X-ray double-crystal characterization of highly perfect InGaAs/InP grown by vapor-phase epitaxy (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 442-446 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Rocking curves of a 0.78-μm layer grown on a 3.35° off-(100) substrate by the hydride process have been compared to detailed calculations using x-ray dynamical diffraction theory. The observed linewidth and peak convoluted reflecting power of the (400) reflection are 32 arc s and 12.4% as compared to calculated values of 26.6 arc s and 17.4%. We used a symmetric (100) InP first crystal, and the calculations were made for this exact geometry. Anomalous dispersion was not neglected. We report the observation of Bragg geometry Pendellosung fringes for this InGaAs layer. As many as six fringes having a separation of 26 arc s were found to be clearly visible. This spacing was fit to obtain the layer thickness. We conclude that, so far as we are aware, our material is the best, as judged from an x-ray point of view, ever reported for the vapor-phase epitaxy process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336650
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