A1 Journal article (refereed)
Correlated effects of fluorine and hydrogen in fluorinated tin oxide (FTO) transparent electrodes deposited by sputtering at room temperature (2021)

Morán-Pedroso, M., Gago, R., Julin, J., Salas-Colera, E., Jimenez, I., de Andrés, A., & Prieto, C. (2021). Correlated effects of fluorine and hydrogen in fluorinated tin oxide (FTO) transparent electrodes deposited by sputtering at room temperature. Applied Surface Science, 537, Article 147906. https://doi.org/10.1016/j.apsusc.2020.147906

JYU authors or editors

Publication details

All authors or editors: Morán-Pedroso, María; Gago, Raúl; Julin, Jaakko; Salas-Colera, Eduardo; Jimenez, Ignacio; de Andrés, Alicia; Prieto, Carlos

Journal or series: Applied Surface Science

ISSN: 0169-4332

eISSN: 1873-5584

Publication year: 2021

Volume: 537

Article number: 147906

Publisher: Elsevier BV

Publication country: Netherlands

Publication language: English

DOI: https://doi.org/10.1016/j.apsusc.2020.147906

Publication open access: Not open

Publication channel open access: 

Abstract

The optical and electrical properties of fluorinated tin oxide (FTO) films deposited at room temperature by sputtering have been investigated varying the fluorine content and the hydrogen atmosphere. The complex behavior of the obtained films is disclosed using a wide set of characterization techniques that reveals the combined effects of these two parameters on the generated defects. These defects control the electrical transport (carrier density, mobility and conductivity), the optical properties (band gap and defects-related absorption and photoluminescence) and finally promote the amorphization of the samples. H2 in the sputtering gas does not modify the H content in the films but induces the partial reduction of tin (from Sn4+ to Sn2+) and the consequent generation of oxygen vacancies with shallow energy levels close to the valence band. A variation of up to four orders of magnitude in electrical conductivity is reported in samples with the appropriate fluorine doping and hydrogen fraction in the sputtering gas, maintaining excellent optical transparency. Optimized room temperature grown electrodes reach sheet resistance ~20 Ω/□ and transparency >90%. This room temperature deposition process enables film preparation on flexible organic substrates, such as polyethylene terephthalate (PET), with identical performance of doubtless interest in flexible and large scale electronics.

Keywords: thin films; optical properties; electric properties

Free keywords: transparent conductive materials; fluorinated tin oxide; room temperature film preparation

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2021

JUFO rating: 1