Photoplastic effect in II-VI semiconductors: The role of hole redistribution in dislocation glide

Photoplasticity in semiconductors, characterized by the modification of plastic deformation under light, has long been recognized but its underlying mechanisms remain elusive. Here, we integrated quantum mechanics (QM) simulations with nanoindentation experiments to investigate the impact of light-induced electron-hole pairs on the plastic deformation in two typical II-IV semiconductors: ZnS and CdTe. For ZnS, the QM simulations indicate an increase in the energy for breaking the Zn-S bond within the S-core dislocation in its glide process, due to the redistribution of excited holes. This enhancement in bond energy elevates the energy barrier for dislocation glide, eventually saturating at high electron-hole concentrations and leading to reduced dislocation mobility in ZnS under light. These findings align well with the nanoindentation experiments, which demonstrate an increase followed by a plateau in the hardness of ZnS under light. In contrast, CdTe exhibits a reduced energy barrier for the glide of Te-core dislocation due to the lack of hole redistribution, likely causing an enhanced dislocation mobility.