Phase Selectivity in Cr and N Co-Doped TiO2 Films by Modulated Sputter Growth and Post-Deposition Flash-Lamp-Annealing

Abstract

In this paper, we report on the phase selectivity in Cr and N co-doped TiO 2 (TiO 2 :Cr,N) sputtered films by means of interface engineering. In particular, monolithic TiO 2 :Cr,N films produced by continuous growth conditions result in the formation of a mixed-phase oxide with dominant rutile character. On the contrary, modulated growth by starting with a single-phase anatase TiO 2 :N buffer layer, can be used to imprint the anatase structure to a subsequent TiO 2 :Cr,N layer. The robustness of the process with respect to the growth conditions has also been investigated, especially regarding the maximum Cr content (<5 at.%) for single-phase anatase formation. Furthermore, post-deposition flash-lamp-annealing (FLA) in modulated coatings was used to improve the as-grown anatase TiO 2 :Cr,N phase, as well as to induce dopant activation (N substitutional sites) and diffusion. In this way, Cr can be distributed through the whole film thickness from an initial modulated architecture while preserving the structural phase. Hence, the combination of interface engineering and millisecond-range-FLA opens new opportunities for tailoring the structure of TiO 2 -based functional materials.

Advanced Strategies in Thin Films Engineering by Magnetron Sputtering

“…The paper "Phase Selectivity in Cr and N Co-Doped TiO 2 Films by Modulated Sputter Growth and Post-Deposition Flash-Lamp-Annealing" by Gago et al presents how the interface engineering strategy can vary the phase occurrence in Cr and N co-doped TiO 2 (TiO 2 :Cr,N) sputter-deposited films [24]. A post-deposition flash-lamp-annealing (FLA) is also used to favor anatase phase, and to give rise to dopant activation and diffusion.…”

TiO2 Phase Engineering by Millisecond Range Annealing for Highly Efficient Photocatalysis

“…The band gap reduction is one of the most common approaches to increase the PC activity of titania. It can be done by alloying TiO 2 with metals (e.g., Mn and Cr) or non-metal elements like nitrogen. − After alloying, the band gap is reduced and, hence, it increases the visible-light absorption . Unfortunately, the alloying often reduces the crystal quality and the energy of photogenerated electrons, which has a negative effect on the PC efficiency.…”