Abstract
Both cubic and rhombohedral forms of boron arsenides were made by the vapor‐phase technique. Energy gaps of the cubic and rhombohedral forms were estimated to be 1.46 and 1.51 ev, respectively, by the optical transmission technique of powdered samples. Mixed crystals of boron arsenide‐gallium arsenide were also prepared by vapor‐transport reaction. Variation of energy gaps from 1.36 to 1.27 ev was observed within the mixed crystal composition range containing 0.8 to 2.8 w/o (weight per cent) of boron. Measurements of effects of temperature and injection level on the emission of diodes prepared from these mixed crystals indicate that all compositions up to 2.8 w/o of boron are direct semiconductors.