Rhodium-Alloyed Beta Gallium Oxide Materials: New Type Ternary Ultra-Wide Bandgap Semiconductors

Beta gallium oxide (β-Ga₂O₃) is an ultra-wide-bandgap semiconductor with advantages for high-power electronics. However, the power resistance of β-Ga₂O₃-based devices is still much lower than its material limit due to its flat band dispersion at its valence band maximum (VBM) and the difficulty for p-type doping. Here, β-Ga₂O₃-based new type ternary ultra-wide bandgap semiconductors: β-(Rh_xGa_1-x)₂O₃’s alloys are reported with x up to 0.5. The energy and band-dispersion curvature of β-Ga₂O₃’s VBM are significantly enhanced via Rh-alloying. Compared to that in β-Ga₂O₃, the β-(Rh_xGa_1-x)₂O₃’s VBMs increase more than 1.35 eV. The hole mass of β-(Rh_0.25Ga_0.75)₂O₃ is only 52.3% of that in β-Ga₂O₃. The decreased hole mass is correlated with the equal Rh─O bond along the b-axis. Thanks to the simultaneous rise of conduction band minimums, the bandgaps of β-(Rh_xGa_1-x)₂O₃ are still much larger than that in commercial silicon carbide. Moreover, the alloys show direct bandgaps in a wide range of x, and a direct and ultra-wide bandgap of 4.10 eV is determined in β-(Rh_0.3125Ga_0.6875)₂O₃. Combined with the enhanced valence energy, reduced hole mass, and ultra-wide bandgap, the β-(Rh_xGa_1-x)₂O₃ can be candidate semiconductors for a new generation of power electronics, ultraviolet optoelectronics, and complementary metal-oxide-semiconductor (CMOS) technologies.