Molecular Dynamics Simulations of CdTe / CdS Heteroepitaxy - Effect of Substrate Orientation

Molecular dynamics simulations were used to catalogue atomic scale structures of CdTe films grown on eight wurtzite (wz) and zinc-blende (zb) CdS surfaces. Polytypism, grain boundaries, dislocations and other film defects were detected. Dislocation lines were distributed in three distinct ways. For the growths on the wz {0001} and zb {111} surfaces, dislocations were found throughout the epilayers and formed a network at the interface. The dislocations within the films grown on the wz {1100}, wz {1120}, zb {110}, zb {010}, and zb {1/10 1 1/10} surfaces formed an interface network and also threaded from the interface towards the film’s surface. In contrast, the growth on the zb {112} surface only had dislocations localized to the interface. This film exhibited a different orientation from the substrate to reduce the lattice mismatch strain energies, and therefore, its misfit dislocation density. Our study indicates that the substrate orientation could be utilized to modify the morphology of dislocation networks in lattice mismatched multi-layered systems.