title: Effects of hydrogen in working gas on valence States of oxygen in sputter-deposited indium tin oxide thin films.
abstract: 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 In(2)O(3) 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 In(2)O(3) band structure and proper concentration of the O(2-) vacancy are indispensable for achieving the highest conductivity; however, the O(-) state lowers efficiency of the carrier doping using the O(2-) vacancy in the lattice and increases density of the ionized scattering center for the carriers.
authors.affiliation: Department of Materials Science, Kyushu Institute of Technology, 1-1 Sensui, Tobata, Kitakyushu 804-8550, Japan.
authors.forename: Suning
authors.initials: S
authors.lastname: Luo
authors.forename: Shigemi
authors.initials: S
authors.lastname: Kohiki
authors.forename: Koichi
authors.initials: K
authors.lastname: Okada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kohno
authors.forename: Takayuki
authors.initials: T
authors.lastname: Tajiri
authors.forename: Masao
authors.initials: M
authors.lastname: Arai
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ishii
authors.forename: Daiichiro
authors.initials: D
authors.lastname: Sekiba
authors.forename: Masanori
authors.initials: M
authors.lastname: Mitome
authors.forename: Fumiya
authors.initials: F
authors.lastname: Shoji