Two-dimensional cubic phase Ga2O3with highly anisotropic mobility and robust wide-bandgap.

The electronic and transport properties of the 2D cubic-Ga2O3 are systematically explored using Heyd-Scuseria-Ernzerhof (HSE) and Perdew-Burke-Ernzerhof functionals, as well as deformation potential theory, indicating the superior structural stability of the cubic monolayer compared with that of cleaved 2D β-Ga2O3. Accurate HSE calculation reveals an indirect bandgap of about 4.44 eV, which is composed of a flat valence band maximum with largely O-2p orbitals and a slight Ga-3d contribution as well as a dispersive conduction band minimum and formed mainly by Ga-4s orbitals, illustrating that n-type conduction is readily achievable.Applying 6% strain modulation, the ~10% bandgap change is observed due to the bond length variations. The calculated electron mobilities for unstrained 2D cubic-Ga2O3 are 1801.70 cm 2 V 1 s 1 along x direction and 240.78 cm 2 V 1 s 1 along y direction, which are comparable to those of perfect 2D β-Ga2O3 but are far exceed the values of bulk β-Ga2O3. Under 6% strain, electron mobilities increase to 3997.60 and 434.44 cm 2 V 1 s 1 along x and y directions, respectively. With 6% biaxial strains, the mobility anisotropy is ranged from 6.92 to 9.20, which is substantially larger than the value of 1.82 in 2D β-Ga2O3 and indicating a strong directional dependence of electron transport at room temperature. The 2D cubic-Ga2O3 combines excellent anisotropic electron mobility, a stable bandgap and an intrinsically flexible structure, highlighting its considerable promise for nanoscale electronic device applications and flexible device technologies.