Photoluminescence from GaN nanopowder: The size effect associated with the surface-to-volume ratio

Nanosized GaN powder with the average grain size changing from similar to 10 to similar to 30 nm has been obtained by combustion method with some modifications and its optical properties have been investigated by photoluminescence (PL). The GaN band-gap-related PL band at similar to 3.4 eV and surface-related PL bands centered at similar to 2.0 and similar to 2.8 eV have been observed for this powder. The relative intensities between observed PL bands change in favor of the surface-related PL band with the decrease of the grain size. This phenomenon has been attributed to the change in the surface-to-volume ratio. (c) 2006 American Institute of Physics.