Band gap, electronic structure, and surface electron accumulation of cubic and rhombohedral In_2O_3

摘要

The bulk and surface electronic structure of In_2O_3 has proved controversial, prompting the current combined experimental and theoretical investigation. The band gap of single-crystalline In_2O_3 is determined as 2.93 ±0.15 and 3.02 ±0.15 eV for the cubic bixbyite and rhombohedral polymorphs, respectively. The valence-band density of states is investigated from x-ray photoemission spectroscopy measurements and density-functional theory calculations. These show excellent agreement, supporting the absence of any significant indirect nature of the In_2O_3 band gap. Clear experimental evidence for an s-d coupling between In 4d and O 2s derived states is also observed. Electron accumulation, recently reported at the (001) surface of bixbyite material, is also shown to be present at the bixbyite (111) surface and the (0001) surface of rhombohedral In_2O_3.