Local internal quantum efficiency of a green light emitting InGaN/GaN quantum well

Abstract

Excitation density-dependent microphotoluminescence measurements were performed on a green light (515 nm) emitting InGaN/GaN multiquantum well sample of low threading dislocation density (5 × 10⁷ cm⁻²). For the observed structure we find a different shape of the local internal quantum efficiency (IQE) curve at spots of different efficiency. Evaluation of the measured local IQE curves in terms of the standard model including Shockley–Read–Hall (SRH), radiative recombination, and a third order loss term (droop) leads to the conclusion that SRH nonradiative recombination varies spatially on a sub-micrometer length scale while both other terms remain constant.