Effect of thermal damage on optical and structural properties of In 0.08Ga0.92N/In0.02Ga0.98N 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 In0.08Ga0.92N/ In0.02Ga0.98N 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/2θ 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. ？ 2004 Elsevier B.V. All rights reserved.