Investigations on cleavage fracture mechanism and surface damage of indium phosphide by molecular dynamics simulation

Abstract

The quality and undamaged size in the resonant cavity surface directly affect the operational stability and output power of semiconductor lasers. To meet the demand for large-size and high-quality mirror facets, a deep understanding of fracture mechanisms of mechanical cleavage is essential. Nevertheless, 3D models of cleavage fracture are rarely investigated. In this work, a molecular dynamics study on the cleavage mechanisms of indium phosphide is reported through examining the effects of the cleavage gap, scratch depth, and cleavage rate on the cleavage damage morphology. The proposed molecular dynamics approach provides insights into the details of cleavage fracture at the atomic level. The simulation results reveal that the cleavage fracture mechanism includes the deviation of cracks between adjacent cleavage surfaces. The predominant damage manifestations on the cleavage surfaces are mainly characterized by cleavage terraces that begin at the bottom of the scratched groove. The cleavage terraces propagate along the [001] crystal direction on the (110) cleavage surface and deviate from their path. This phenomenon is essentially related to the stress released during the crack propagation process. Compared with the cleavage gap and scratch depth, the cleavage rate significantly affects the critical cleavage load. Additionally, a good correlation between the density of the cleavage terraces and the maximum undamaged length is achieved and reasonably explained. Mastering the correlation between various cleavage conditions and cleavage surface damage will facilitate and guide the fabrication of nanoscale resonant cavity mirrors and advance the development of mechanical cleaving processes.