Unraveling intrinsic mobility limits in two-dimensional (AlxGa1−x)2O3 alloys.

β-(Al_xGa_1−x)₂O₃ presents a diverse material characterization exhibiting exceptional electrical and optical properties. Considering the miniaturization of gallium oxide devices, two-dimensional (Al_xGa_1−x)₂O₃ alloys, as a critical component in the formation of two-dimensional electron gases, demand an in-depth examination of their carrier transport properties. Herein, we investigate the temperature-dependent carrier mobility and scattering mechanisms of quasi-two-dimensional (2D) (Al_xGa_1−x)₂O₃ (x ≤ 5) by solving the Boltzmann transport equation from first-principles. Anisotropic electron mobility of 2D (Al_xGa_1−x)₂O₃ is limited to 30−80 cm²/Vs at room temperature, and it finds that the relatively large ion-clamped dielectric tensors (Δɛ) suggest a major scattering role for polar optical phonons. The mobility of 2D (Al_xGa_1−x)₂ is less than that of bulk β-(Al_xGa_1−x)₂O₃ and shows no quantum effects attributed to the dangling bonds on the surface. We further demonstrate that the bandgap of 2D (Al_xGa_1−x)₂O₃ decreases with the number of layers, and the electron localization function also shows an anisotropy. This work comprehensively interprets the scattering mechanism and unintentional doping intrinsic electron mobility of (Al_xGa_1−x)₂O₃ alloys, providing physical elaboration and alternative horizons for experimental synthesis, crystallographic investigations, and power device fabrication of 2D (Al_xGa_1−x)₂O₃ atomically thin layered systems. [ABSTRACT FROM AUTHOR]