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 (GaxIn1-x)2O3 solid solution system was investigated by using combinatorial synthesis. At a low Ga content of (GaxIn1-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 (GaxIn1-x)2O3 solid solution system were strongly affected by Ga2O3; however, the valence band maximum position shifted to a higher binding energy.