Confinement induced decrease of the exciton-longitudinal optical phonon coupling in GaN quantum dots

Abstract

We report on an investigation of the coupling between excitons and longitudinal optical phonons as a function of GaN quantum dot size. Photoluminescence measurements of the quantum dots from cryogenic temperatures up to above room temperature are presented. The experiments were performed on ensembles of AlN capped GaN quantum dots grown on an Al0.15Ga0.85N surface by means of metalorganic vapor phase epitaxy. The results are analyzed on the basis of a Bose–Einstein-type expression describing the exciton to longitudinal optical phonon coupling of the dots as a function of the lattice temperature. A reduction of the exciton to LO-phonon coupling with decreasing quantum dot size was found.