Effects of Peierls barrier and epithreading dislocation orientation on the critical thickness in heteroepitaxial structures

We have extended the mechanical equilibrium theory of J. W. Matthews and A. E. Blakeslee [J. Cryst. Growth 27, 118 (1974)] (MB) for determining the critical thickness in semiconducting heteroepitaxial films by including the effect of the Peierls barrier. The new formulation allows an evaluation of the dependence of critical thickness on the orientation of epithreading dislocation, and a comparison of theoretical predictions with measurements indicates that a knowledge of the epithreading dislocation orientation is necessary in predicting critical thicknesses in heteroepitaxial structures. In this formulation, the effect of the Peierls barrier is to bring the theoretical critical thicknesses closer to experimental values as compared to the predictions of the MB theory.