Applied Surface Science 288 (2014) 201–207 Contents lists available at ScienceDirect Applied Surface Science j ourna l ho me page: www.elsevier.com/locate/apsusc TiO 2 anatase films obtained by direct liquid injection atomic layer deposition at low temperature L. Avril a,∗ , S. Reymond-Laruinaz a , J.M. Decams b , S. Bruyère a , V. Potin a , M.C. Marco de Lucas a , L. Imhoff a a Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex, France b Annealsys, rue de la Vieille Poste, 34055 Montpellier Cedex 1, France a r t i c l e i n f o Article history: Received 4 July 2013 Received in revised form 30 September 2013 Accepted 2 October 2013 Available online 11 October 2013 Keywords: Anatase TiO2 DLI-ALD Infrared heating Raman spectroscopy a b s t r a c t TiO 2 thin films were grown by direct liquid injection atomic layer deposition (DLI-ALD) with infrared rapid thermal heating using titanium tetraisopropoxide and water as precursors. This titanium tetraiso- propoxide/water process exhibited a growth rate of 0.018 nm/cycle in a self-limited ALD growth mode at 280 ◦ C. Scanning electron microscopy and atomic force microscopy analyses have shown a smooth surface with a low roughness. XPS results demonstrated that the films were pure and close to the TiO 2 stoichiometric composition in depth. Raman spectroscopy revealed that the films were crystallized to the anatase structure in the as-deposited state at low temperature without necessity of high temper- ature annealing. Results obtained demonstrate that the liquid injection ALD is an efficient method of elaborating titanium oxide films using titanium tetraisopropoxide as precursor. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Titanium dioxide (TiO 2 ) has many attractive physico-chemical properties and thus lends itself to various applications such as opti- cal coatings for anti-reflection and solar cells [1–3], high dielectric layers for electronic devices [4], biocompatible coatings for bio- materials [5]. TiO 2 layers have been obtained by many physical and chemical deposition techniques [6,7]. Among these techniques, atomic layer deposition (ALD) has recently received great attention for the growth of TiO 2 thin films [8,9]. While chemical vapour depo- sition (CVD) provides that the precursors are sent at the same time, ALD mechanism is based on two surface reactions, avoiding any gas phase reaction between the different precursors during the growth. ALD permits to deposit many oxides at very low temperature (down to 100 ◦ C) in comparison with the other chemical deposition tech- niques, allowing deposition on thermally fragile materials such as organic ones [10,11]. Indeed higher deposition temperature affects on the properties of films deposited on sodalime glass substrates [12,13], due to sodium diffusion. Moreover, ALD film growth is self- limited and based on surface reactions, which results in a control of the film growth at the atomic scale. ∗ Corresponding author. Tel.: +33 380396332. E-mail address: ludovic.avril@u-bourgogne.fr (L. Avril). The deposition of TiO 2 films is currently obtained by ALD by using different precursors. The most widely investigated precur- sors are titanium tetrachloride (TiCl 4 ) and water [14,15]. However, the corrosive nature of the reaction by HCl product is considered as a drawback [16]. Thus, alternative precursors like titanium tetraiso- propoxide, titanium ethoxide, and titanium methoxide [17–19] have been tested in recent years. The direct liquid injection (DLI) deliver system is a promising technology which differs fundamen- tally from bubbler systems used in CVD system [20–22]. In a DLI system, the precursor is dissolved in a solvent and this solution is kept at room temperature until it is transported into the vapor- izer chamber. The vapor deliver depends on control of a liquid flow instead of a gas flow, offering the controlled supply of the precur- sor solution. Moreover, the liquid injection is able to handle most of the solid and liquid compounds including low vapor pressure, thermally labile and viscous ones. The DLI use for the synthesis of thin films by metal organic chemical vapour deposition (MOCVD) and atomic layer deposition has been reported by several authors [23–26]. Among all the TiO 2 properties, the photocatalytic activity is applied for purification [27] and air cleaning [28]. It is shown that the anatase phase is generally more efficient as oxidative photocat- alyst than common TiO 2 phases including amorphous, rutile and brookite titanium dioxide [29–31]. Low temperature deposition is of particular interest since special substrates capable of withstand- ing high temperatures are not needed, thereby reducing production 0169-4332/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apsusc.2013.10.007