Strain tunable excitonic optical properties in monolayer Ga₂O₃

Abstract

Two-dimensional (2D) Ga2O3 has been confirmed to be a stable structure with five atomic layer thickness configuration. In this work, we study the quasiparticle electronic band structures and then access the excitonic optical properties through solving the Bethe-Salpeter equation (BSE). The results reveal that the exciton dominates the optical absorption in the visible light region with the binding energy as large as ~1.0 eV, which is highly stable at room temperature. Importantly, both the dominant absorption P1 and P2 peaks are optically bright without dark exciton between them, and thus is favorable for luminescence process. The calculated radiative lifetime of the lowest-energy exciton is 2.0×10-11 s at 0 K. Furthermore, the radiative lifetime under +4% tensile strain is one order of magnitude shorter than that of the strain-free case, while it is less insensitive under the compressive strain. Our findings set the stage for future theoretical and experimental investigation on monolayer Ga2O3.