A new semiconductor alloy material, GaAs1-x Bi x has been created by Metal Organic Vapor Phase Epitaxial (MOVPE) growth. A low growth temperature, such as 365°C, is required to obtain the alloy. X-ray diffraction measurements of alloy layers reveal that the diffraction patterns are satisfactory. The maximum GaBi content in the GaAsBi alloy estimated from the lattice constant is around 2%, which is consistent with that estimated from secondary ion mass spectroscopy (SIMS) measurements. In a photoluminescence (PL) measurement, a single peak spectrum is observed from 10 to 300 K. The temperature variation of the PL peak energy is as small as 0.1 meV/K.

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It is demonstrated that the energy band gap in epitaxial layers is changed by biaxial elastic strains which are produced by lattice mismatches in heterostructures. The epitaxial layers used in this work were Gax In1−xP layers grown on (001) GaAs substrates by liquid phase epitaxy. The energy band-gap shifts were determined by comparing the photoluminescence peak energies of the as-grown GaxIn1−xP layers with those from free-standing layers removed from the GaAs substrates. It was experimentally found that the energy band gap shifts linearly with the elastic strain in the layer. Assuming that the lattice mismatch was accommodated only by the elastic distortion, the energy band-gap shifts in Ga0.5In0.5P alloys were also calculated. The calculated results are 6.0 eV or 4.9×10−12 eV/dyn cm−2 per unit strain or stress, respectively, for the [100] and [010] biaxial elastic stress. These values are in quite good agreement with the experimental results.

The characteristics of GaAs 1Àx Bi x semiconductor alloy layers grown by metalorganic vapor phase epitaxy (MOVPE) have been studied. GaAs 1Àx Bi x epilayers were obtained on GaAs substrates. The lattice constants of the alloy were found to increase with the addition of Bi. The uniformity and the reproducibility of the solid composition of the GaAs 1Àx Bi x epilayers are good in spite of the difficulty of epitaxial growth. Although layer growth was performed at a low temperature (365 C), the stability of GaAs 1Àx Bi x alloy was sufficient for device processing, which was demonstrated by annealing in an arsenic atmosphere at 560 C for 30 min. The photoluminescence (PL) spectra show that the PL peak energy of the GaAs 1Àx Bi x alloy shifts to a longer wavelength with increasing Bi content. The temperature dependence of the PL peak energy is much weaker than the temperature variation of the band gap of GaAs; the temperature dependence of the PL peak energy of the GaAs 0:974 Bi 0:026 layer is less than one-third the temperature variation of the band gap of GaAs. The results obtained in this research support the hypothesis that III-V alloy semiconductors consisting of semiconductor and semimetal components have a temperature-insensitive band gap.

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