Predictive modeling of misfit dislocation induced strain relaxation effect on self-rolling of strain-engineered nanomembranes

Combining atomistic simulations and continuum modeling, the effects of misfit dislocations on strain relaxation and subsequently self-rolling of strain-engineered nanomembranes have been investigated. Two representative material systems including (GaN/In_0.5Ga_0.5N) of wurtzite lattice and II-VI materials (CdTe/CdTe_0.5S_0.5) of zinc-blend lattice were considered. The atomistic characteristics of dislocation and the resulting lattice distorting were first determined by generalized-stacking-fault energy profile and disregistry function obtained through Peierls-Nabarro model. Those properties were then used to calculate the accurate mismatch strain of those nanomembranes with the presence of dislocations, and as inputs into von-Karman shell theory to quantitatively evaluate the effects on self-rolling curvature and anisotropy. The theoretical results were further confirmed by atomistic simulations of different crystal geometries and dislocation configurations. Our results provide essential theoretical insights towards prediction and design of rollup configurations for strain-engineered nanomembranes containing crystalline defects.