Collective formation of misfit dislocations at the critical thickness for equilibrium nanowire heterostructures

In this work we model the evolution of strain energy during different growth stages of heterostructure nanowires. We find that the minimum energy configuration changes abruptly from fully elastically strained to partially relaxed at the critical thickness. The transition at the critical thickness, when the crystal growth is close to equilibrium, is associated with a collective formation event of misfit dislocations. These insights are based on a technique developed to simulate misfit dislocations in a finite element framework, incorporating both elastic and plastic relaxation in a stationary heterostructure. We argue that these results have general relevance for mismatched heterostructures.