Optical properties of nanocrystalline GaN films prepared by DC magnetron sputtering

Nanocrystalline GaN films with different crystallite size were prepared by direct current (DC) magnetron sputtering technique under different substrate temperature. The sizes of nanocrystals derived from grazing-incidence X-ray diffraction (GIXRD) peaks were 4 nm and 7 nm for films grown at 770 K and 870 K, respectively. The Raman peak centered at 657 cm(-1) might be primarily attributed to a V-N-related band in the nanocrystalline GaN. The similar broad near-band-edge emission peak about 356 nm characterized by photoluminescence (PL) was observed and no yellow luminescence can be found.