Crystal structure prediction of three- and two-dimensional gallium oxide via differential evolution algorithm

Wide-band-gap semiconductor gallium oxide (Ga2O3) has significant advantages for use in high-power semiconductor devices and deep-ultraviolet-detection optoelectronic devices. Crystal structure prediction is one of the most challenging and interesting issues in condensed matter science. In this work, 11 three-dimensional (3D) Ga2O3 structures and four two-dimensional (2D) Ga2O3 structures were predicted and screened based on a multi-objective differential evolution algorithm combined with density functional theory (DFT) calculations. Two low-energy 3D structures proved to be consistent with previously characterized β-Ga2O3 (C2/m) and α-Ga2O3 (R3̄c). Their stabilities were confirmed by calculation of their structural parameters, phonon spectra, elastic constants, and elastic moduli. Their photoelectric properties were also investigated. The results showed that both the stable 3D and 2D Ga2O3 structures had wide band gaps, and some of them exhibited good optical properties. These findings are of great significance in providing theoretical guidance for the structural design of Ga2O3 materials and their application in microelectronic and photoelectric devices.