Effects of carrier localization on the optical characteristics of MOCVD-grown InGaN/GaN heterostructures

Abstract

We have studied both the spontaneous and stimulated emission (SE) properties as a function of excitation photon energy for InGaN/GaN multiple quantum wells (MQWs). A significant redshift of the SE peak with decreasing excitation photon energy was observed as the excitation photon energy was tuned below a certain photon energy ("mobility edge") for the InGaN/GaN MQWs, with similar behavior observed for the spontaneous emission. The relative position of the mobility edge with respect to the absorption edge and the spontaneous and stimulated emission peak positions indicates the emission originates from carriers localized by extremely large potential fluctuations in the InGaN active layers of the MQWs. Therefore, carrier localization in the InGaN active regions explains the observed spontaneous and stimulated emission behaviors of these materials.