Strain relaxation and interfacial stability in III–V semiconductor strained-layer heteroepitaxy: atomistic and continuum modeling and comparisons with experiments

Abstract

A systematic study is presented of interfacial stability and strain relaxation through misfit dislocation formation in III–V semiconductor layer-by-layer heteroepitaxy. A multiscale modeling strategy is developed that links continuum elasticity theory with atomistic structural relaxation and Monte Carlo simulations using a valence force field description of interatomic interactions. Results are presented for the energetics of the transition from a coherent to a semicoherent film/substrate interface consisting of a misfit dislocation network, the semicoherent interface structures, the associated strain fields, and the film surface morphological characteristics for InAs epitaxy on GaAs(1 1 1)A. The capability of continuum elasticity theory to provide a satisfactory description of the atomistic simulation results is discussed. In addition, using thin compliant substrates and grading the composition of the deposited film are demonstrated to have beneficial effects on film strain relaxation. Furthermore, the dynamics of strain relaxation is analyzed based on a phenomenological mean-field theoretical framework. Our theoretical results are in very good agreement with our experimental measurements on InAs/GaAs(1 1 1)A samples for films grown by molecular beam epitaxy on thick and thin GaAs buffer layers.