Indium doping-assisted monolayer Ga 2 O 3 exfoliation for performance-enhanced MOSFETs.

Monolayer (ML) GaO with outstanding properties is promising for advanced nanodevice applications; however, its high exfoliation energy makes obtaining it challenging. In this study, we propose a more efficient solution to obtain ML GaO by exfoliation from indium-doped bulk β-GaO. The exfoliation efficiency with the assistance of In-doping and the doping influence on the stability and structural and electronic properties of ML GaO are systematically studied using first-principles calculations. The exfoliation energy of ML GaO is found to be reduced by 28% and is of the same order of magnitude as that of typical van der Waals (vdWs) 2D materials. Besides, excellent stability is preserved for ML GaO at extremely high In doping concentration by phonon spectrum and molecular dynamics inspections. The bandgap of ML GaO decreases from 4.88 to 4.25 eV with increased In concentration, and the modification of the VBM converts ML GaO to a direct bandgap semiconductor. With the suppression of ZA mode phonon scattering, the pristine and In-doped ML GaO exhibit high electron mobility, whereas the strong electron-phonon coupling (EPC) effect significantly decreases the hole mobility. Finally, the transfer characteristics of 5 nm MOSFETs based on the pristine and In-doped ML GaO with varied In concentrations are simulated based on the non-equilibrium Green's function (NEGF) formalism. The for HP has a maximum of 3060 μA μm at In doping concentration of 5% and is triple that of the pristine ML GaO for LP at In doping concentration of 20%. The FOMs of n-type MOSFETs based on the In-doped ML GaO and typical 2D materials are compared and shows huge potential for sub-5 nm applications. Our study applies a new strategy for obtaining ML GaO and can also improve the device performance at the same time.