Stress and morphology evolution during the heteroepitaxial growth of group III-nitrides

In this study, in-situ wafer curvature measurements were used to monitor the evolution of film stress during MOCVD growth of GaN and AlGaN. These studies were carried out using a multi- beam optical stress sensor (MOSS) incorporated onto a custom-designed vertical cold-wall MOCVD reactor. The MOSS system provides real-time information on growth rate and changes in substrate curvature which are related to film stress via a modified version of Stoney´s equation. Post-growth structural characterization including atomic force microscopy, X-ray diffraction and transmission electron microscopy was used to correlate measured changes in film stress to film morphology evolution.