Resonant photoluminescence excitation studies of InGaN/GaN single quantum wells

The optical properties of InGaN/GaN single quantum well structures, with indium fractions of 0.15 and 0.25, have been studied under resonant excitation conditions. The low temperature (T=6 K) photoluminescence spectra show a broad recombination feature that we attribute to acoustic phonon accompanied absorption and emission from a distribution of localized states. Also we observe in the sample with the indium fraction of 0.15 a sharp line that we attribute to LO phonon accompanied recombination of excitons in the resonantly excited localized states. Comparing the form of the spectra with model calculations, where we consider the deformation potential coupling of localized excitons to an effectively continuous distribution of acoustic phonons, enables us to show that the in-plane localization length scale of the excitons may be as small as 2.5 Aa. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)