It was recalled that dislocations formed in epitaxial thin films, above a critical thickness, when the stress due to the film/substrate mismatch became excessive. This behavior was extensively investigated in non piezo-electric thin films. In piezo-electric films, the mismatch strain field and the electric field were coupled and the critical thickness depended upon the electric field. The critical thickness for dislocation formation in a piezo-electric film was derived here, and the dependence of the critical thickness upon the piezo-electric properties of the AlxGa1-xN/GaN system was considered.

Critical Thickness for Dislocation Generation in Epitaxial Piezoelectric Thin Films. B.Wang, C.H.Woo, Q.Sun, T.X.Yu: Philosophical Magazine, 2003, 83[31-34], 3753-64