MISFIT DISLOCATION GENERATION MECHANISMS IN HETEROSTRUCTURES

Experimental data on the critical thickness show agreement with equili brium models when epitaxial bicrystals are investigated, but large dis crepancies when semiconductors are investigated. This discrepancy is l argely due to two factors. The data are typically not from samples at equilibrium and the equilibrium models do not account for the friction al forces on dislocations. This paper presents a model of misfit dislo cation generation which incorporates the frictional forces and is ther eby a constrained-equilibrium model. The kinetics of the approach to t he constrained equilibrium are also presented. Application of the resu lting equations to experimental data show reasonable agreement for het erostructures of semiconductors as well as of metals. Most of the data available in the literature are not in a condition of constrained equ ilibrium and are ever further from the equilibrium state. It is theref ore important to adopt a kinetic model to account for the experimental measurements of critical thickness and strain relaxation with deposit thickness.