关键词: excitons, radiative lifetime, Ga$_{2}$O$_{3}$

Abstract: Two-dimensional (2D) Ga$_{2}$O$_{3}$ has been confirmed to be a stable structure with five atomic layer thickness configuration. In this work, we study the quasi-particle 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 $\sim 1.0$ eV, which is highly stable at room temperature. Importantly, both the dominant absorption P$_{1}$ and P$_{2}$ 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$\times10^{-11}$ 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 Ga$_{2}$O$_{3}$.

Key words: excitons, radiative lifetime, Ga$_{2}$O$_{3}$