TIO2 THIN-FILMS BY ATOMIC LAYER DEPOSITION - A CASE OF UNEVEN GROWTH AT LOW-TEMPERATURE

Atomic layer deposition of TiO2 thin films from TiCl4 and H2O at 150 d egrees C was found to result in nonhomogeneous film growth as a functi on of time. The unevenness of the growth was ascertained by in situ op tical interference technique. In order to obtain a more detailed under standing of the growth behavior, AFM, SEM, EPMA, RHEED, XRD, and XPS m easurements were performed on a series of films of different thickness . The data obtained allow us to relate the peculiarities of the growth to the appearance of anatase inclusions in the amorphous base layer o f TiO2 followed by their development into crystalline particles. We ma naged to delimit the nucleation stage of the growth, the stage of the full coverage of the substrate with the amorphous Nm, the stage of the origination of the anatase inclusions, and the final stage at which t he polycrystalline film is deposited. The increase of crystallinity an d roughness was correlated with the increase of the film thickness and quantitatively determined. It was found that in our films the composi tion of both the crystalline and amorphous part corresponds to TiO2 st oichiometric phase, and that the films contain 0.3 mass% of Cl. (C) 19 98 Elsevier Science B.V. All rights reserved.