Optical properties of InN films grown by MBE at different conditions

InN films were grown by N/sub 2/ plasma-assisted molecular beam epitaxy (MBE) on Al/sub 2/O/sub 3/ substrate with different growth temperature T/sub s/ (from 200/spl deg/C to 500/spl deg/C). It was found that high crystal quality of InN films can be grown at higher temperature. The optical absorption measurement showed the band-gap energy of InN films decreases with increasing of the growth temperature. The photo-luminescence measurement indicated the band gap of InN films grown at 500/spl deg/C was located about 1.0-1.1 eV.