Reactively-sputtered super-hydrophilic ultra-thin titania films deposited at 120 °C

Abstract

We investigate super-hydrophilic TiO _2 (titania) films for concentrated solar-thermal power applications. Reactive magnetron sputtering has been used to deposit 8 to 12 nm thick titania thin films onto borosilicate microscope glass slides, low-Fe extra-clear architectural glass, or Si(100) wafers with a 500 nm thick thermal SiO _2 layer. The effects of deposition temperature and O _2 fraction of the O _2 /Ar working gas were investigated. We demonstrate the importance of the O _2 fraction for obtaining optically transparent, super-hydrophilic (contact angle below 1°) thin films. In particular, we show that as the O _2 fraction increases, contact angle decreases, obtaining super-hydrophilic titania thin films at deposition temperatures as low as 120 °C. Our work enables to develop low thermal budget cost-efficient industrial synthesis processes, paving the way for commercial applications.

Keywords

• super-hydrophilic
• titania
• reactive sputtering
• thin films
• CSP