Open Access Nano Express

High-rate low-temperature dc pulsed magnetron sputtering of photocatalytic TiO2films: the effect of repetition frequency

J Šícha1, D Heřman1, J Musil1*, Z Strýhal2 and J Pavlík2

Author Affiliations

1 Department of Physics, University of West Bohemia, Univerzitní 22, Pilsen, 306 14, Czech Republic

2 Department of Physics, J.E. Purkyně University, České mládeže 8, Usti nad Labem, 400 96, Czech Republic

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Nanoscale Research Letters 2007, 2:123-129  doi:10.1007/s11671-007-9042-z

Published: 27 February 2007

Abstract

The article reports on low-temperature high-rate sputtering of hydrophilic transparent TiO2thin films using dc dual magnetron (DM) sputtering in Ar + O2mixture on unheated glass substrates. The DM was operated in a bipolar asymmetric mode and was equipped with Ti(99.5) targets of 50 mm in diameter. The substrate surface temperature Tsurfmeasured by a thermostrip was less than 180 °C for all experiments. The effect of the repetition frequency frwas investigated in detail. It was found that the increase of frfrom 100 to 350 kHz leads to (a) an improvement of the efficiency of the deposition process that results in a significant increase of the deposition rate aDof sputtered TiO2films and (b) a decrease of peak pulse voltage and sustaining of the magnetron discharge at higher target power densities. It was demonstrated that several hundreds nm thick hydrophilic TiO2films can be sputtered on unheated glass substrates at aD = 80 nm/min, Tsurf < 180 °C when high value of fr = 350 kHz was used. Properties of a thin hydrophilic TiO2film deposited on a polycarbonate substrate are given.

Keywords:
TiO2film; Hydrophilicity; Deposition rate; Unheated substrate; Dual magnetron sputtering; Polycarbonate