The Relaxation of InxGa1-xAs/GaAs Strained Multilayers

Abstract

AbstractIn this paper we report on the kinetics of strain relaxation in GaAs/InxGa1-xAs/GaAs/AlAs (0.05<x<0.22) layers grown by MBE on GaAs at 520°C. We have characterized the density of dislocations present due to strain relaxation during both film growth and processing by using a large area thinning technique which enables the observation of approximately 2 mm2 areas by plan-view TEM. The thickness of the InxGa1-xAs layers studied was 36.4 nm and four compositions were chosen so that the critical thickness predicted by strain energy considerations was exceeded. Due, however, to sluggish dislocation nucleation and glide kinetics at the deposition temperature, the as-grown misfit dislocation densities were well below the predicted level for fully relaxed films. We have studied the rate at which these metastable strained films relax as a function of post-growth annealing time and temperature.