Abstract
Indium tin oxide (ITO) is one of the most widely used transparent conductors in optoelectronic device applications. We investigated the optical properties of ITO thin films at high temperatures up to 800 °C using spectroscopic ellipsometry. As temperature increases, amorphous ITO thin films undergo a phase transition at ~ 200 °C and develop polycrystalline phases with increased optical gap energies. The optical gap energies of both polycrystalline and epitaxial ITO thin films decrease with increasing temperature due to electron-phonon interactions. Depending on the background oxygen partial pressure, however, we observed that the optical gap energies exhibit reversible changes, implying that the oxidation and reduction processes occur vigorously due to the low oxidation and reduction potential energies of the ITO thin films at high temperatures. This result suggests that the electronic structure of ITO thin films strongly depends on temperature and oxygen partial pressure while they remain optically transparent, i.e., optical gap energies > 3.6 eV.
Document Type
Article
Publication Date
7-27-2020
Digital Object Identifier (DOI)
https://doi.org/10.1038/s41598-020-69463-4
Funding Information
We acknowledge the support of NASA Kentucky under NASA award number NNX15AR69H (for high-temperature optical measurements) and a National Science Foundation grant DMR-1454200 (for thin-film synthesis and characterization). J.K. acknowledges the support from the Global Ph.D. Fellowship Program (2015H1A2A1034200) through the NRF Korea funded by the Ministry of Education.
Repository Citation
Kim, Jiwoong; Shrestha, Sujan; Souri, Maryam; Connell, John G.; Park, Sungkyun; and Seo, Ambrose, "High-Temperature Optical Properties of Indium Tin Oxide Thin-Films" (2020). Physics and Astronomy Faculty Publications. 667.
https://uknowledge.uky.edu/physastron_facpub/667
Supplementary information
Notes/Citation Information
Published in Scientific Reports, v. 10, issue 1, article no. 12486.
© The Author(s) 2020
This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.