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We present photoluminescence and transmission measurements of vapor-grown GaTe crystals. The ground-state 1S triplet and singlet excitonic peaks are well resolved in the optical photoluminescence spectra from high-quality crystals, the triplet state lying -1.6 meV lower in energy than the singlet state. The emission intensity ratio of these two peaks is close to the 3:1 ratio of their spin multiplicities. The 1S singlet-state emission is strongly polarized perpendicular to the crystal b axis, whereas the emission from the triplet state is partially polarized along the crystal b axis. Transmission spectra also indicate that the absorption corresponding to the n=1 exciton is made up of two peaks, of which the higher-energy one is observed only for light polarized perpendicular to the b axis. Two small peaks on the lower-energy side of the photoluminescence triplet peak are believed to correspond to 1S singlet and triplet excitons bound to a strain-induced defect center.

Epitaxial growth of SiC films was performed on 4H SiC n+ substrates utilizing a chlorosilane/propane chemistry in both single wafer and batch CVD systems. Variations of the chlorosilane flow under fixed conditions of gas composition, temperature and pressure resulted in growth rates between 4 to 20 μm/hr. Fixing the chlorosilane flow rate to achieve a growth rate of approximately 4 μm/hr, the effects of temperature, pressure and gas composition on background dopant incorporation, epitaxial layer uniformity and epitaxial defect generation were investigated. Intentional n and p-type doping has been demonstrated over the carrier range 1×1018-1×1020/cm3. This paper presents the first reported of use of chlorosilane precursors to grow high quality undoped, n and p doped SiC epilayers.