Molecular Beam Expitaxy Research Articles

Parabolic quantum wells with theGaAs−AlxGa1−xAssystem

Photoluminescence measurements at 5 K on wafers containing parabolic quantum wells fabricated by molecular-beam expitaxy with the GaAs-${\mathrm{Al}}_{0.3}$${\mathrm{Ga}}_{0.7}$As system reflect harmonic oscillator-like electron and hole levels. The many observed heavy-hole transitions can be fitted accurately with a model that divides the energy-gap discontinuity ${\ensuremath{\Delta}E}_{g}$ equally between the conduction and valence-band wells. This is in marked contrast to the usual ${\ensuremath{\Delta}E}_{c}=0.85{\ensuremath{\Delta}E}_{g}$ and ${\ensuremath{\Delta}E}_{v}=0.15{\ensuremath{\Delta}E}_{g}$ generally assumed for square wells. Experiment and theory show that parabolic wells can lead to parity-allowed $\ensuremath{\Delta}n=2$ ("forbidden") transitions with strengths greater than that of nearby $\ensuremath{\Delta}n=0$ ("allowed") transitions.

VA-3 state-of-the-art K-band GaAs power field-effect transistors prepared by molecular beam expitaxy

VA-3 state-of-the-art K-band GaAs power field-effect transistors prepared by molecular beam expitaxy

NiSi2-Si infrared Schottky photodetectors grown by molecular beam epitaxy

We report the first infrared sensitive (λ≳1 μm) Schottky photodetector using nickel disilicide (NiSi2) grown expitaxially on a silicon substrate by molecular beam expitaxy. Measurements utilizing the 1.32-μm line of a neodymium yttrium aluminum garnet (Nd:YAG) laser indicate a barrier height of 0.64 eV and a quantum efficiency of 0.22%. The use of silicon technology has the potential of integrating the detector with electronics on a monolithic chip of silicon. Such systems are attractive for optical communication applications in the 1.3-μm wavelength region.

Substrate effect on the lattice constants of the MBE-grown In1−xGaxAs and GaSb1−yAsy

We have analyzed the lattice constants of InAs and GaSb grown on GaAs using molecular beam expitaxy (MBE). The observed deviations between the MBE and bulk samples, especially for GaSb, can be largely accounted for by the thermal stress induced in the films. Our analysis indicates that a similar thermal stress could cause ≲ 20% variation in alloy compositions of In1−xGaxAs required to match the lattices of two GaSb1−yAsy films which have the same y but are separately grown on GaAs and GaSb substrates.

Double heterostructure Pb1−xSnxTe waveguides at 10.6 μm

High−optical−quality planar waveguides have been fabricated in the Pb1−xSnxTe alloy system by molecular beam expitaxy. The structures consist of a 6−μm−thick low−carrier−concentration (≲4×1016 cm−3) Pb0.92Sn0.08Te layer vacuum deposited on an n−type PbTe substrate followed by a second 0.5−μm−thick epitaxial layer of n−type PbTe. The measured propagation loss of ⩽1.5 cm−1 (6.5 dB/cm) for TE−polarized 10.6−μm laser radiation in these waveguides at 77 K is sufficiently low for integrated optical circuits in this wavelength range, and the waveguide fabrication techniques are compatible with those used for lasers and detectors in Pb1−xSnxTe epitaxial layers.