Microstructure and optical properties of nanocrystalline GaN embedded in silica matrix

Monodispersed and high-density nanocrystalline GaN particles were in situ synthesized in silica xerogel by a sol-gel method. Microstructure and morphology analyses reveal that as-prepared GaN crystallites were hexagonal phase. It is well dispersed in silica matrix with uniformed size, and its average size varied from 3 to 8 nm with prolonging the nitridation period and enhancing the reaction temperature. The FTIR spectrum shows a GaN bond stretch present at 600 cm^-1, which indicated that the element Ga atom dominantly existed with GaN bond in the samples. Room temperature photoluminescence (PL) exhibited a non-size-dependence near band-edge emission of GaN at 390 nm and another PL emission peak about 565, 570, 580 nm with different intensity in three samples, respectively. The possible reason for the PL results was proposed.