Optical recombination processes in high-quality GaN films and InGaN quantum wells grown on facet-initiated epitaxial lateral overgrown GaN substrates

We have used time-resolved and temperature-dependent photoluminescence (PL) measurements to study the recombination mechanism in high-quality GaN film s and InGaN quantum wells (QWs) grown on facet-initiated epitaxial lateral overgrown (FIELO) GaN substrates. We found that the nonradiative defect den sity in FIELO-GaN films is much lower than that in GaN films frown on sapph ire substrates and that the emission efficiency of InGaN-QWs is determined not only by the defect density but also by the indium alloy fluctuation. We have proposed a model to evaluate these two factors separately and have us ed it to show that both the defect density and the alloy fluctuation in the QW films frown on FIELO substrates are much less than those in QW films gr own on sapphire substrates.