Ž . Thin Solid Films 371 2000 126131 PECVD of amorphous TiO thin films: effect of growth 2 temperature and plasma gas composition G.A. Battiston a, , R. Gerbasi a , A. Gregori a , M. Porchia a , S. Cattarin b , G.A. Rizzi c a ICTIMA-CNR, Corso Stati Uniti 4, I-35127 Pado a, Italy b IPELP-CNR, Corso Stati Uniti 4, I-35127 Pado a, Italy c Uni  ersita di Pado a, Dipartimento CIMA-Via Loredan 4, I-35131 Pado a, Italy ` Received 6 February 2000; received in revised form 28 April 2000; accepted 28 April 2000 Abstract Amorphous TiO thin films are grown using a r.f. plasma-enhanced chemical vapour deposition process at substrate 2 temperatures between 393 and 523 K using titanium tetraisopropoxide as a precursor, and Ar or N , pure or mixed with O , as 2 2 the plasma gas. All films are smooth and adherent, their roughness slightly increases by increasing the substrate temperature or if oxygen is added to the plasma gas. Films grown in the presence of oxygen result transparent in the visible region and highly resistive, as expected for pure titanium dioxide. Films grown in an oxygen-free plasma appear grey  blue and fairly conductive Ž . suggesting the presence of Ti III species. The operating conditions provide high deposition rates, up to 37 nmmin in the presence of oxygen.  2000 Elsevier Science S.A. All rights reserved. Ž . Keywords: Chemical vapour deposition CVD ; Plasma processing and deposition; Titanium nitride; Titanium oxide 1. Introduction Ž . The chemical vapour deposition CVD technique has many peculiarities such as good step coverage, uniformity and relatively low cost. In order to lower the deposition temperature of CVD processes two ap- Ž proaches are possible: Plasma Enhanced CVD PE- . Ž . CVD and Metal Organic CVD MOCVD and, as a natural development, PE-CVD used together with a Ž . metallorganic precursor PE-MOCVD . Thermal MOCVD in the range 630  700 K was al- ready widely used to deposit good-quality polycrys-   talline TiO thin films 1,2 . Deposition of pure amor- 2 phous TiO thin films by remote plasma enhanced 2  Corresponding author. Tel.: 39-049-829-5948; fax: 39-049- 870-2911. Ž . E-mail address: g.a.battiston@nt.ictr.pd.cnr.it G.A. Battiston . CVD using titanium tetraisopropoxide in argon with deposition rates up to 15 nmmin is reported by Frenck   et al. 3 . Successively Lee et al. 4 studied the deposi- tion of amorphous stoichiometric TiO thin films in a 2 r.f. plasma CVD reactor using titanium tetraisopropox- ide and oxygen, obtaining deposition rates generally lower than 1 nmmin. More recently, Electron Cy- clotron Resonance PE-CVD has been successfully ap- plied to the preparation of single layer crystalline TiO 2   5 and double layer SiO TiO coatings 6 . Titanium 2 2 Ž . tetraisopropoxide and tetrakis alkylamido titanium Ž have been employed in different plasma processes d.c., . glow discharge, electron cyclotron resonance to grow Ž . Ž .   Ti NCO , Ti NC or TiN 7  11 . The aim of this work was to grow TiO thin films by 2 PE-MOCVD and, by varying properly the plasma com- position, to modulate the properties of the deposited films such as composition, morphology, resistivity and quantum efficiency of photoconversion. 0040-609000$ - see front matter  2000 Elsevier Science S.A. All rights reserved. Ž . PII: S 0 0 4 0 - 6 0 9 0 00 00998-6