Tunable bulk photovoltaic effect in strained $\gamma$-GeSe

TL;DR

This study investigates how uniaxial strain affects the shift current in the newly synthesized polar phase of GeSe, revealing tunability, potential topological phase transitions, and implications for bulk electronic state characterization.

Contribution

It provides the first first-principles analysis of strain-tunable shift current in $ ext{γ}$-GeSe, highlighting the possibility of strain-induced topological phase transitions.

Findings

Shift current can be enhanced up to ~20 μA/V² with strain.

Direction of shift current can be inverted by light strain.

Anomalous zero-frequency behavior suggests band inversion and topological transition.

Abstract

Recently, Lee \textit{et. al.} [Nano Lett. \textbf{21}, 4305 (2021)] newly synthesized monochalcogenide GeSe in a polar phase, referred to as $\gamma$-phase. Motivated by this work, we study shift current of $\gamma$-GeSe and its tunability via an in-plane uniaxial strain. Using first-principles calculations, we uncover the electronic structure of the strained $\gamma$-GeSe systems. We then calculate frequency-dependent shift current conductivities at various strains. The tunability is demonstrated to enhance the shift current up to $\sim$ 20 $\mu$A/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 $\gamma$-GeSe.