Misfit dislocation generation mechanisms in heterostructures

Abstract

Experimental data on the critical thickness show agreement with equilibrium models when epitaxial bicrystals are investigated, but large discrepancies when semiconductors are investigated. This discrepancy is largely due to two factors. The data are typically not from samples at equilibrium and the equilibrium models do not account for the frictional forces on dislocations. This paper presents a model of misfit dislocation generation which incorporates the frictional forces and is thereby a constrained-equilibrium model. The kinetics of the approach to the constrained equilibrium are also presented. Application of the resulting equations to experimental data show reasonable agreement for heterostructures of semiconductors as well as of metals. Most of the data available in the literature are not in a condition of constrained equilibrium and are ever further from the equilibrium state. It is therefore important to adopt a kinetic model to account for the experimental measurements of critical thickness and strain relaxation with deposit thickness.