Calculations were made of elastic strain relaxation in wurtzite semiconductor/insulator structures. The elastic strain tensor components, elastic energy, and density of misfit dislocations were obtained as functions of the AlN layer thickness. It was found that the theoretical values of the elastic strain relaxation were in satisfactory agreement with experimental data that were extracted from the capacitance-voltage characteristics of GaN/AlN/GaN structures. The results confirmed that the gradual relaxation process began at an AlN film thickness of 3nm. The uniform contributions to the elastic strain tensor components decreased by about an order of magnitude when the film thickness increased from 3 to 10nm. At the same time as this decrease, there was an increase in a non-uniform contribution that was due to misfit dislocations. The dislocation interactions led to the redistribution of dislocations within the 3 to 6nm range of AlN film thicknesses.

A.D.Bykhovski, B.L.Gelmont, M.S.Shur: Journal of Applied Physics, 1995, 78[6], 3691-6