Tunable Electronic, Transport, and Optical Properties of Fluorine and Hydrogen Passivated Two-Dimensional Ga2O3 by Uniaxial Strain

Two-dimensional (2D) semiconductors have shown great prospect in future-oriented optoelectronic applications, whereas the applications of conventional 2D materials are significantly impeded by the low electron mobility (≤ 200 cm2V1s1). In this work, strain mediated fluorine and hydrogen passivated 2D Ga2O3 systems (FGa2O3H) have been explored via using first-principles calculations with the Heyd-Scuseria-Ernzerh (HSE) and Perdew-Burke-Ernzerhof (PBE) functional. Our results reveal a considerable high electron mobility of FGa2O3H up to 4863.05 cm2V1s1 as the uniaxial tensile strain reaches 6%, which can be attributed to the enhanced overlapping of wave functions and bonding features. Overall, applying the uniaxial strain monotonously along a(b) direction from compressive to tensile cases, the bandgaps of 2D FGa2O3H increase initially and then decrease, which is originated from the changes of σ* anti-bonding in the CBM and π bonding states in the VBM accompanying with the lengthening Ga-O bonds. Additionally, when the tensile strain is larger than 8%, the stronger π bonding at G point leads to an indirect-to-direct transition. Besides the highest electron mobility of n-type doped 2D FGa2O3H with 6% tensile strain, the electrical conductivity is enhanced and further elevated with the temperature increase from 300K to 800K. The variations of the absorption coefficient in the ultraviolet region is negligible with the increasing tensile strain from 0% to 6%, shed light on its applications in high-power optoelectronic devices.