Surface emission characteristics of ZnO nanoparticles

Nanometer-sized ZnO particles sized from 17 nm to 110 nm were prepared by homogenous precipitation method (HPM). Photoluminescence (PL) spectra of as-prepared nanoparticles excited at 320 nm were fitted with Gaussian curves, in which six Gaussian peaks gave a good accordance with corresponding photon transitions. We observed that the relative amplitude of Gaussian combination at the lowest transition energy decreases rapidly with increased grain size. Such sensitive size-dependence shows a key role of the surface recombination in PL of nanosized structures due to large surface-to-volume ratio. The novel size dependence of PL intensity can be suitably attributed to the surface related mechanism.