Molecular beam epitaxy growth of boron-containing nitrides

Layers of BN, BGaN and BAlN were grown by molecular beam epitaxy using ammonia on (0001) sapphire substrates. The crystal structure and material quality of these layers were assessed by reflection high energy electron diffraction, x-ray diffraction, Fourier transform infrared reflectance, and photoluminescence spectroscopy. These measurements reveal that while BN layers grow as polycrystalline films, BGaN and BAlN layers grow as single crystals with boron composition up to 2% and 6%, respectively. A monotonic increase in the band gap energy and a decrease in c-lattice constant were observed with increasing boron concentrations in BGaN samples. Yellow-band emission and increased surface roughening were also observed in samples with higher boron compositions. (C) 1999 American Vacuum Society. [S0734-211X(99)02703-1].