Exploring the structural, electronic, and transport properties in thickness-dependent two-dimensional Ga₂O₃ induced by native defects

Understanding the effects of native oxygen vacancy (VO) and gallium vacancy (VGa) in two-dimensional (2D) Ga2O3 semiconductors is critical for optimizing device efficiency and developing innovative applications. In this work, the structural stability, electronic structure, carrier mobility and conductivity of thickness-dependent 2D Ga2O3 induced by native VO and VGa are systematically studied utilizing first-principles calculations, deformation potential (DP) and Boltzmann transport theories. In Ga2O3VO configuration, the newly occupied mid-gap states primarily composed of O-2p, Ga-3p, and Ga-3d orbitals are formed, demonstrating a deep donor feature. The created impurity levels can act as the hole compensation center and lower the bandgaps of monolayer, bilayer, and trilayer Ga2O3VO to 1.60, 1.64, and 1.53 eV, respectively. The electron mobility exhibits a high value up to ~ 12154.89 cm2V1s1 in bilayer Ga2O3VO. Shallow acceptor states primarily composed of O-2p and Ga-3d orbitals are introduced for Ga2O3VGa configuration, suggesting the effective p-type doping behavior. The bandgaps of monolayer, bilayer, and trilayer Ga2O3VGa are of respectively 2.31, 1.90, and 1.84 eV, accompanying with the monotonous decreasing of hole mobilities from 261.46 to 85.75 cm2V1s1 along x-direction. Meanwhile, the n-type and p-type conductivities are elevated and decreased respectively with the increase of layer thickness, which are endowed with the similar trends as that of carrier mobilities. Distinct dimensional induced band features and transport properties have been resolved in VO and VGa cases. Our comprehensive investigations of vacancy-deficient 2D Ga2O3 demonstrate the high carrier mobility and strong anisotropic, which highlight the understanding of native defects for improving the performance of 2D Ga2O3-based electronic and optoelectronic devices.