Tunable electronic, transport, and optical properties of fluorine- and hydrogen-passivated two-dimensional Ga2O3 by uniaxial strain

Abstract Two-dimensional (2D) semiconductors have shown great prospects for future-oriented optoelectronic applications, whereas the applications of conventional 2D materials are significantly impeded by their low electron mobility (⩽200 cm 2 V −1 s −1 ). In this work, strain-mediated fluorine- and hydrogen-passivated 2D Ga 2 O 3 systems (FGa 2 O 3 H) have been explored via using first-principles calculations with the Heyd–Scuseria–Ernzerh and Perdew–Burke–Ernzerhof functionals. Our results reveal a considerable high electron mobility of FGa 2 O 3 H up to 4863.05 cm 2 V −1 s −1 as the uniaxial tensile strain reaches 6%, which can be attributed to the enhanced overlapping of wave functions and bonding features. Overall, when applying uniaxial strain monotonously along the a ( b ) direction from compressive to tensile cases, the bandgaps of 2D FGa 2 O 3 H increase initially and then decrease, which originates from the changes of σ * anti-bonding in the conduction band minimum and π bonding states in the valence band maximum accompanying the lengthening Ga–O bonds. Additionally, when the tensile strain is larger than 8%, the stronger π bonding at the G point leads to an indirect-to-direct transition. Besides the highest electron mobility observed in n-type doped 2D FGa 2 O 3 H with 6% tensile strain, the electrical conductivity is enhanced and further elevated as the temperature increases from 300 K to 800 K. The variations of the absorption coefficient in the ultraviolet region are negligible with increasing tensile strain from 0% to 6%, which sheds light on its applications in high-power optoelectronic devices.