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

Abstract Beta gallium oxide ( β ‐Ga 2 O 3 ) is an ultra‐wide‐bandgap semiconductor with advantages for high‐power electronics. However, the power resistance of β ‐Ga 2 O 3 ‐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 ‐Ga 2 O 3 ‐based new type ternary ultra‐wide bandgap semiconductors: β ‐(Rh x Ga 1‐x ) 2 O 3 ’s alloys are reported with x up to 0.5. The energy and band‐dispersion curvature of β ‐Ga 2 O 3 ’s VBM are significantly enhanced via Rh‐alloying. Compared to that in β ‐Ga 2 O 3 , the β ‐(Rh x Ga 1‐x ) 2 O 3 ’s VBMs increase more than 1.35 eV . The hole mass of β ‐(Rh 0.25 Ga 0.75 ) 2 O 3 is only 52.3% of that in β ‐Ga 2 O 3 . 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 x Ga 1‐x ) 2 O 3 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 0.3125 Ga 0.6875 ) 2 O 3 . Combined with the enhanced valence energy, reduced hole mass, and ultra‐wide bandgap, the β ‐(Rh x Ga 1‐x ) 2 O 3 can be candidate semiconductors for a new generation of power electronics, ultraviolet optoelectronics, and complementary metal‐oxide‐semiconductor (CMOS) technologies.