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Notes: InAs1−xSbx films have been successfully grown by molecular-beam epitaxy on (100) GaAs substrates. Long wavelength photoluminescence spectra have been obtained reproducibly in the 3–5 and 8–12 μm spectral ranges in III-V compound semiconductors.

Notes: InAs1−xSbx films have been successfully prepared by molecular beam epitaxy on (100) InAs substrates. Long-wavelength photoluminescence has been investigated over the complete compositional range. Luminescence peak wavelengths as long as 8 μm have been obtained for the first time among III-V compound semiconductor materials in spite of the existence of a large lattice mismatch. These results are indicative of high-quality material.

Notes: The equilibrium in-plane lattice parameter for lattice mismatched multilayers, as first derived by Matthews and Blakeslee [J. Cryst. Growth 32, 265 (1976)], has been used to obtain an expression for the misfit between the multilayers as a whole and a lattice mismatched substrate. The resulting expression immediately suggests a correspondence between the multilayers as a whole and a single coherently strained layer of equal thickness but having a misfit equal to the misfit between the constituent layers spatially averaged over a single repeat distance. The present results are obtained without reference to the energy density of a misfit dislocation. In particular, the present correspondence allows one to predict the critical thickness of coherently strained multilayers if single-layer critical thicknesses are known.

Notes: Estimates of the anticipated band alignments for pseudomorphic InP/InxGa1−xAs heterostructures for growth on (001) InP are presented; wherein 0≤x≤1.0. Linearity and transitivity of the valence-band offset, ΔEv, are assumed for a given in-plane lattice parameter, a(parallel)≡a0(InP). Valence-band offsets for ternary heterojunctions are obtained via linear interpolation of the self-consistent interface calculations of Van deWalle and Martin (unpublished), whereas ΔEv for the lattice matched (In, Ga) As/InP heterojunction is taken as an input parameter. It is found that ΔEc shows a rather gradual increase for 0≤x〈0.53, with an abrupt change in slope for x〉0.53. The present estimates imply an increase in ΔEc by more than 0.2 eV as x→1.0 relative to the lattice matched value, and that the partitioning of ΔEg between conduction and valence band in strained heterostructures maintains its lattice matched value. Potential applications are reviewed in brief.

Notes: Pressure-tuned resonance Raman scattering (RRS) experiments in Ga1−xInxAs/Ga1−yAlyAs strained-layer quantum-well samples with x=0.15 and y=0.15, on a GaAs substrate, are reported. The photoluminescence (PL), 2LO-, and LO-phonon Raman-scattered intensities were followed as a function of pressure using the diamond cell. In backscattering geometry and with (100) samples, three sharply defined 2LO-phonon resonances are observed, at 2.1, 3.8, and 5.2 GPa, with 647.1-nm excitation ((h-dash-bar)ωL=1.916 eV), and these are identified to be from the AlGaAs, GaAs, and InGaAs layers, respectively. At the above pressures, the 2LO peak of the layer falls right on top of the PL peak of the corresponding layer, revealing that the resonance occurs when E0=(h-dash-bar)ωS (2LO). For the LO-phonon intensity, maxima are observed at 2.8 and 4.7 GPa, respectively, from the AlGaAs layer and GaAs substrate. While the LO-resonance profile (pressure versus phonon intensity) for the AlGaAs layer is narrow, the profile of the GaAs substrate layer is highly asymmetric. The InGaAs LO-resonance is totally masked by the strong GaAs LO phonon. The pressure dependence of the E0 gap, determined from PL data, reveals that the resonance condition for 2LO is E0=(h-dash-bar)ωS (2LO) and, for LO, E0=(h-dash-bar)ωL. Results with samples of different Al content and (h-dash-bar)ωL are consistent with the above conditions. A brief discussion of the theory of the RRS cross section is given, and it is suggested that the observed 2LO-resonance scattering is dominated by Frölich interaction, and that it could be a double resonance. The asymmetry in the LO resonance of the GaAs substrate, we believe, is due to the pressure-induced transparency, and this is a problem when dealing with pressure-tuned RRS, in multiple-quantum-well structure with GaAs or AlGaAs substrates. The usefulness of the 2LO resonance in locating the E0 gap is indicated, and the indistinguishability between luminescence and Raman scattering at the center of the 2LO resonance is pointed out. The need to study photoluminescence and Raman scattering in pressure-tuned RRS experiments is emphasized.

Notes: A simple three-dimensional vapor phase model is used to interpret and clarify the selective area growth process. The model predicts both normal and anomalous profiles of thickness and composition, including long range effects. These are verified by an extensive set of experiments. © 1999 American Institute of Physics.

Notes: Stimulated emission, obtainable at high optical pumping levels, has been used to follow the pressure dependence of the Γ-band gap of molecular beam epitaxial In0.53Ga0.47As on (001)InP. Hydrostatic pressure was generated using a diamond anvil cell, and all measurements were made at room temperature. The gap varies sublinearly with pressure for P(approximately-greater-than)10 kbar, having an initial slope of 12.44 meV/kbar. The deviation from a linear behavior is largely due to nonlinearities in the equation of state at higher pressures. The deformation potential (Xid+ (1)/(3) Xiu−a) =−(7.79±0.4)eV, for the Γ-band gap.

Notes: We report a new photoluminescence defect spectrum with a no-phonon transition at 1.0192 eV which emerges in many silicon layers grown on silicon substrates by molecular beam epitaxy. Comparison of the no-phonon transition and the chief local mode ((h-dash-bar)ω=7.5 meV) to the well-established Cu-related spectrum at 1.0145 eV suggests that the new defect incorporates Cu as well. Deep level transient measurements support the presence of Cu in the epilayers. We suggest that this defect spectrum has recently been observed by others but was not identified and associated with Cu.

Notes: Performance characteristics of a pseudomorphic p-type, normal incidence, Ge0.25Si0.75/Si strained-layer quantum well infrared photodetector on (001) Si is described for 20≤T≤77 K. The device shows broadband photoresponse (8–14 μm) which is attributed to strain and quantum confinement induced mixing of heavy, light, and split-off hole bands. Typical device responsivity at λ=10.8 μm is ∼0.04 A/W over the 20–77 K temperature range. A detectivity D*λ=3.3×109 cm (square root of)Hz/W was measured at a bias of −2.4 V for a temperature of 77 K at λ=10.8 μm and no cold shield. Room temperature FTIR measurements yield a quantum efficiency η≈3.1% at λp≈8 μm at 300 K.