Photoindentation: A New Route to Understanding Dislocation Behavior in Light
Atsutomo Nakamura, Xufei Fang, Ayaka Matsubara, Eita Tochigi, Yu Oshima, Tatsushi Saito, Tatsuya Yokoi, Yuichi Ikuhara, Katsuyuki Matsunaga
Abstract
It was recently found that extremely large plasticity is exhibited in bulk compression of single-crystal ZnS in complete darkness. Such effects are believed to be caused by the interactions between dislocations and photoexcited electrons and/or holes. However, methods for evaluating dislocation behavior in such semiconductors with small dimensions under a particular light condition had not been well established. Here, we propose the "photoindentation" technique to solve this issue by combining nanoscale indentation tests with a fully controlled lighting system. The quantitative data analyses based on this photoindentation approach successfully demonstrate that the first pop-in stress indicating dislocation nucleation near the surface of ZnS clearly increases by light irradiation. Additionally, the room-temperature indentation creep tests show a drastic reduction of the dislocation mobility under light. Our approach demonstrates great potential in understanding the light effects on dislocation nucleation and mobility at the nanoscale, as most advanced technology-related semiconductors are limited in dimensions.