Transparent high conductive Titanium oxynitride nanofilms obtained by nucleation control for sustainable optolectronics

Abstract

Transparent conducting thin films have attracted a lot of interest in last decades because they have become essential electrodes for optoelectronics applications. Indium tin oxide (ITO) is the transparent conductor par excellence with 80% transmittance in the visible range and a resistivity of 10−4 Ω·cm. Unfortunately, ITO is toxic, brittle and very expensive due to the Indium scarcity in the earth's crust. For this reason, sustainable alternatives are being sought. Titanium oxynitrides are a very interesting alternative, titanium is abundant and its oxynitrides show remarkable mechanical, electrical and optical properties that can be tailored by modifying the N/O ratio. However, achieving the balance between transparency and conductivity to design a suitable electrode is a challenging milestone. In this work we prepared high quality TiON nanofilms by PLD (pulsed laser deposition) in vacuum, tuning the transparency and conducting properties by varying the deposition laser energy to control the N/O ratio. The absence of gases flux achieves defect-free films with transparency up to 50% and similar conductivity to ITO (1.8·102 S/cm). These results open a new line of research for the development of sustainable transparent conducting electrodes based on dense and planar TION films, very useful for electronic and optical devices, solar cells or photonics.