Valence Band Modification of a (GaxIn1–x)2O3 Solid Solution System Fabricated by Combinatorial Synthesis

The correlation between the crystal structure and valence band structure of a (Ga_xIn_1–x)₂O₃ solid solution system was investigated by using combinatorial synthesis. At a low Ga content of (Ga_xIn_1–x)₂O₃ with a single-phase cubic In₂O₃ crystal structure, a surface electron accumulation layer (SEAL), which is an important electrical phenomenon in In₂O₃, was confirmed. When the Ga content increased to approximately x = 0.4, mixed crystal structures of Ga₂O₃ and In₂O₃ were produced. Above x = 0.5, the dominant valence band structure was attributed to Ga₂O₃, the SEAL disappeared, and the sheet resistance increased greatly by 5 orders of magnitude or more. The in-gap state and valence band structure of the (Ga_xIn_1–x)₂O₃ solid solution system were strongly affected by Ga₂O₃; however, the valence band maximum position shifted to a higher binding energy.