Influence of oxygen growth pressure on laser ablated Cr-doped In2O3 thin films

Abstract

We present a systematic investigation of the effects of oxygen growth pressure on the structural, optical, and electrical properties of In2O3:Cr thin films grown by pulsed laser deposition. X-ray diffraction analysis showed increases in lattice constant from 10.103 Å to 10.337 Å, and in particle size from 13.9 nm to 35.5 nm as the oxygen growth pressure increased from 7.5 × 10-6 Torr to 7.5 × 10-3 Torr, respectively. The observed shift in the X-ray diffraction peaks to lower angles was assumed to be caused by the reduction in the lattice defect density, precisely oxygen vacancies. The optical transparency increased with partial oxygen pressure , and an average transmittance of ∼85% was obtained at 7.5 × 10-3 Torr. The films are highly conducting with resistivity as low as 2 × 10-4 Ω cm and mobility as high as 133 cm/V s. Temperature dependent resistivity measurements in the 45 < T < 300 K temperature range reveal that films grown at exhibit negative temperature coefficient of resistivity (TCR) below approximately T = 60 K, T = 120 K, T = 160 K; then positive TCR in the temperature intervals 60 < T < 300 K, 120 < T < 300 K, and 160 < T < 300 K, respectively. This suggests that two disparate mechanisms govern electrical dc transport in the two temperature regions. Film grown at of 7.5 × 10-3 Torr displayed typical semiconducting behavior with negative TCR in the whole temperature region.

Department(s)

Physics, Astronomy, and Materials Science

Document Type

Article

DOI

https://doi.org/10.1016/j.apsusc.2009.07.045

Keywords

indium oxide, chromium, transparent conductor, mobility

Publication Date

2009

Journal Title

Applied surface science

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