Feasibility of <i>p</i>-type conduction in beta rhodium alloyed gallium oxide

Abstract

Beta-gallium oxide (β-Ga2O3) has attracted extensive attention in the field of power devices owing to its ultrawide bandgap and well-established synthesis method. However, the lack of p-type conductivity in β-Ga2O3 limits the device performance. Recently, rhodium-alloyed β-Ga2O3, namely, β-(RhxGa1−x)2O3, has been predicted to possess elevated valence band maxima (VBMs) and reduced hole masses. This study explores the feasibility of realizing p-type doping in β-(RhxGa1−x)2O3. The acceptor levels for Li, Na, and Cu dopants in β-(Rh0.25Ga0.75)2O3 are determined to be lower than 0.4 eV from the VBMs. The elevation of the VBM, along with a weak interaction between the dopants' orbitals and the orbitals at the VBMs, plays a crucial role in facilitating the attainment of a shallow acceptor level. At a hole density of 1017 cm−3 and room temperature, the hole mobility of β-(Rh0.5Ga0.5)2O3 is predicted to reach 10.7 cm2 V−1 s−1, which is higher than the values of most p-type metal oxides. Moreover, the hole mobility is determined to be anisotropic, and its magnitude is mainly limited by polar optical phonon scattering. Our work shows that achieving p-type doping in β-(RhxGa1 − x)2O3 alloys is indeed feasible, and the formation of p–n homojunctions based on β-(RhxGa1 − x)2O3 could significantly extend the application scope of alloy oxides.