Nonconservative formation of 〈100〉 misfit dislocation arrays at In0.2Ga0.8As/GaAs(001) interfaces during post-growth annealing

Transmission electron microscopy is applied to investigate the effect of annealing on misfit dislocations in an In0.2Ga0.8As/GaAs(001) heterostructure. In as-grown samples, an orthogonal array of 60° dislocations along 〈110〉 directions is observed in the interface. During annealing, the 60° dislocations along 〈110〉 directions are bent from 〈110〉 directions toward 〈100〉 directions. The process represents a new strain relaxation mechanism in semiconductor heterostructures. As the dislocation segments along 〈100〉 can relieve the strain more effectively than 60° dislocations, we propose that the dislocations move nonconservatively in or near the interface by diffusion along the dislocation cores or in the heterointerface.