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

We report on an investigation of the coupling between excitons and longitud inal optical phonons as a function of GaN quantum dot size. Photoluminescen ce measurements of the quantum dots from cryogenic temperatures up to above room temperature are presented. The experiments were performed on ensemble s 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 temperatur e. A reduction of the exciton to LO-phonon coupling with decreasing quantum dot size was found. (C) 1999 American Institute of Physics. [S0003-6951(99 )03839-5].