Critical thickness and relaxation of (111) oriented strained epitaxial layers

Abstract

Growth on the <111> orientation brings with it new possibilities for nucleation and multiplication mechanisms for misfit relieving defects in epitaxial layers. Yet, despite these changes, the macroscopic relaxation behaviour of good quality In x Ga 1− x As layers on <111> GaAs is remarkably similar to the relaxation behaviour of 〈001〉 oriented layers. Using high resolution X-ray diffraction, we present the full analysis of <111> oriented strained In x Ga 1− x As layers showing the optimum data handling to derive strain and misfit. Data from partially relaxed layers are presented and compared with theoretical equilibrium critical thickness for the <111> orientation. We find that there is excellent agreement between the experimental data and the theory.