Mobile dislocation density and strain relaxation rate evolution during InxGa1−xAs∕GaAs heteroepitaxy

The kinetics of dislocation-mediated strain relaxation have been investigated during InxGa1−xAs∕GaAs molecular beam epitaxy growth. We use in situ curvature measurement to determine the film stress as a function of time during deposition. The relaxation behavior includes a temperature dependent initial relaxation stage which partially relieves the misfit strain, followed by a rapid strain relaxation which commences at a temperature independent thickness and proceeds at a comparable rate at all temperatures studied. We discuss these observations in terms of the mobile dislocation density evolution and the dependence of the strain relaxation rate on the driving force and temperature.