Thermodynamics of polydomain heterostructures. II. Effect of microstresses

Abstract

The thermodynamic effects of microstresses on the formation of polydomain heterostructures are considered. The microstresses arise due to the periodic deviation of the actual misfit from the average misfit on the interfaces between a polydomain layer and neighboring layers. The thermodynamic analysis is restricted to heterostructures with $\text{D/h<1,}$ where $D$ is the period of the polydomain structure, and $h$ is the thickness of the thinner layer of the heterostructure, either active or passive. In this case the long-range interactions between interfaces through their microstresses can be neglected. A simple and effective approximation for the microstress energy in polydomain heterostructures is proposed. Using this approximation, the effect of thickness on the polydomain structure can be included in the thermodynamic theory through the adjustment of the parameter of incompatibility between the domains. If the domain interfaces are mobile, the critical behavior of compliance and susceptibility should be observed at the critical thicknesses of the polydomain layer. These critical thicknesses correspond to loss of stability of the polydomain structure or change of polydomain symmetry.