Tunable bulk photovoltaic effect in strained $γ$-GeSe

Abstract

Recently, Lee et. al. [Nano Lett. 21, 4305 (2021)] newly synthesized monochalcogenide GeSe in a polar phase, referred to as γ-phase. Motivated by this work, we study shift current of γ-GeSe and its tunability via an in-plane uniaxial strain. Using first-principles calculations, we uncover the electronic structure of the strained γ-GeSe systems. We then calculate frequency-dependent shift current conductivities at various strains. The tunability is demonstrated to enhance the shift current up to ∼ 20 µA/V 2 . Moreover, the direction of shift current can be inverted by a light strain. Markedly, an anomalous behavior is found in the zero-frequency limit, which can be an indicative of band inversion and a potential topological phase transition driven by the strain. Our results suggest that shift current can be a tangible prove of bulk electronic states of γ-GeSe.