XPS method as a useful tool for studies of quantum well epitaxial materials: Chemical composition and thermal stability of InGaN/GaN multilayers

Abstract

The XPS technique combined with low energy Ar+ ion sputter depth profiling was used to obtain information about chemical composition and reproducibility of the growth procedure by the MOVPE method of the InGaN multi quantum wells (MQWs). A good in-depth resolution of the XPS depth profiling technique, allows observation of InGaN quantum wells with thickness down to 2nm. However quantitative characterization of very narrow QWs is limited by the elemental detection range of the XPS analysis. Both the InGaN QWs and GaN barriers parameters were well characterized using the model MQWs samples with various QW thickness. Inter-diffusion of indium within the GaN barrier layers, induced by high-temperature annealing, has been detected. This work evidences the successful application of the XPS depth profiling analysis as a very useful tool to optimize the growth parameters and thermal stability of InGaN/GaN MQWs.