Theoretical study of the energetics, strain fields, and semicoherent interface structures in layer-by-layer semiconductor heteroepitaxy

Abstract

A theoretical analysis based on continuum elasticity theory and atomistic simulations is presented of the interfacial stability with respect to misfit dislocation formation, the strain fields, and the film surface morphology during layer-by-layer semiconductor heteroepitaxy. The strain in the coherently strained films, the energetics of the transition from a coherent to a semicoherent interface consisting of misfit dislocation arrays or networks, the structure of the corresponding semicoherent interfaces, the strain fields associated with different equilibrium states of strain, and the morphological characteristics of the film surfaces are calculated for InAs/GaAs(110) and InAs/GaAs(111)A. The thickness of the epitaxial film is used as the dynamical variable in the analysis. Critical film thicknesses for transition from one equilibrium state of strain to another are computed. The analysis is presented for the more general case of heteroepitaxy on a finite-thickness compliant substrate, while the common case of epitaxy on an infinitely thick substrate is derived as an asymptotic limit of the general case. Continuum elasticity theory is found to describe the atomistic simulation results very well, down to the monolayer-thickness limit. Our theoretical results are discussed in the context of recent experimental data.