Structural and optical quality of GaN grown on Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111)

Thick ({approx}900 nm) GaN layers were grown by molecular beam epitaxy on cost-effective Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) substrates and characterized by x-ray diffraction and photoluminescence. Samples grown in Ga-rich condition show superior structural and optical quality with reduced density of cubic GaN inclusions within the hexagonal matrix and a relatively strong photoluminescence emission at 3.45 eV at 10 K. Cubic inclusions are formed in the initial growth stage and their concentration is reduced with increasing film thickness and after rapid thermal annealing.