Thermal relaxation in strained InGaAs/GaAs heterostructures

The kinetics of strain relaxation during annealing of epitaxial InGaAs films grown on GaAs by MOCVD at atmospheric pressure was studied by optical microscopy and transmission electron microscopy. The density of misfit dislocations and crosshatching was measured as a function of annealing temperature and annealing time. These experiments show that the generation of misfit dislocations during the annealing process is thermally activated. The kinetic rate constant increases as thickness increases. After long annealing times, the sample reaches its steady-state condition in which a residual strain apparently still exists. Apparently this residual strain is not accommodated by misfit dislocations and does not change with annealing temperature nor sample thickness.