High-excitation effect on photoluminescence of sol-gel ZnO nanopowder

Abstract

We studied the power-dependent photoluminescence of ZnO nanopowder grown by sol-gel method at low temperature. At moderate optical pumping intensity, two nonlinear emission bands due to the radiative recombination of free biexciton and the inelastic exciton–exciton scattering were detected. We found that the threshold of the excitation density for the emergence of the nonlinear emission bands is low (<18 W/cm2) in sol-gel ZnO nanopowders.