Misfit stress relaxation in wide bandgap semiconductor heterostructures with trigonal and hexagonal crystal structure

Abstract

In this work, we consider film/substrate semiconductor heterostructures with a hexagonal (wurtzite) and trigonal (corundum) crystal structure. We show that the differences between the stress level in the α-Ga2O3/α-Al2O3 heterostructure with the corundum crystal structure and the stress level in the GaN/AlN heterostructure with the wurtzite crystal structure do not exceed 50%. We study the effect of Al composition x and growth direction of the heterostructure on the critical film thickness for misfit dislocation formation in α-(AlxGa1−x)2O3/α-Al2O3 heterostructures. We provide a comparison between theoretical calculations of the critical film thickness and experimental data on the film thickness, at which the misfit dislocations were observed in α-(AlxGa1−x)2O3/α-Al2O3 heterostructures.