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Effects of Hydrogen in Working Gas on Valence States of Oxygen in Sputter-Deposited Indium Tin Oxide Thin Films

2010; American Chemical Society; Volume: 2; Issue: 3 Linguagem: Inglês

10.1021/am9006676

1944-8252

Suning Luo, Shigemi Kohiki, Koichi Okada, Atsushi Kohno, Takayuki Tajiri, M. Arai, Satoshi Ishii, Daiichiro Sekiba, Masanori Mitome, Fumiya Shoji,

Ga2O3 and related materials

X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy−elastic recoil detection analysis (RBS−ERDA) revealed that hydrogen in working gas for dc-plasma sputter deposition resided in indium tin oxide (ITO) films and generated the O− state seen as the suboxide-like O 1s peak in XPS. Growth of the suboxide-like O 1s peak was parallel with an increase of the resided hydrogen quantified by RBS−ERDA. The first-principles band structure calculation revealed that the electronic structure of In2O3 crystal was realized typically for the most conductive as-deposited film grown in the gas containing hydrogen of 1%. The as-deposited film grown in the gas containing hydrogen of more than 1% exhibited rather high density but low mobility of carriers and showed the electronic structure above 4 eV originated from the O− state due to the resided hydrogen in addition to that of the most conducting one. Both well preserved In2O3 band structure and proper concentration of the O2− vacancy are indispensable for achieving the highest conductivity; however, the O− state lowers efficiency of the carrier doping using the O2− vacancy in the lattice and increases density of the ionized scattering center for the carriers.