Effect of thermal damage on optical and structural properties of In 0.08Ga 0.92N/In 0.02Ga 0.98N multi-quantum wells grown by MOCVD

Abstract

Effects of thermal damage on the optical and structural properties of InGaN/InGaN multi-quantum wells (MQWs) were investigated by using photoluminescence (PL), high-resolution X-ray diffraction (HRXRD), and atomic force microscopy (AFM). The five-period In 0.08Ga 0.92N/In 0.02Ga 0.98N MQWs were grown on sapphire using metalorganic chemical vapor deposition (MOCVD). To investigate the influence of thermal damage on InGaN MQWs, the MQW sample was heated to the high-temperature for p-type GaN layer growth and cooled down and its structural and optical properties were compared with the MQW sample cooled down without high-temperature thermal treatment. The surface morphology of InGaN MQWs changes from a spiral to a step structure after the high-temperature treatment, which is induced by the desorption and the surface migration of In and Ga adatoms during the high-temperature treatment. In HRXRD (0 0 0 4) ω / 2 θ scan, the intensity fringes between high-order satellite peaks disappear, which suggests that the interface quality of InGaN MQWs be also deteriorated by high-temperature treatment. Temperature dependence of PL measurement shows that InGaN MQWs without high-temperature thermal treatment had higher internal quantum efficiency and lower localization effect.