Size dependence of exciton-phonon coupling in sol-gel ZnMgO powders

Abstract

We found that the exciton-phonon coupling in the Zn(1-x)Mg(x)O powders (0.01 <= x <= 0.07) is greatly influenced by the crystalline-size. Two well-resolved photoluminescence (PL) bands due to recombination of free exciton and its longitudinal optical (LO)-phonon replicas enable us to analyze the relative intensities among free excitons, one-LO-phonon replicas, and two-LO-phonon replicas. As crystalline size increases, a larger enhancement of the PL-intensity ratio of a free exciton to its LO-phonon replicas was found compared to that of two LO-phonon replica to one-LO-phonon replica. (C) 2011 American Institute of Physics. [doi:10.1063/1.3563574]