AlxTi1-xO (ATO) films were grown by plasma-enhanced atomic layer deposition, using alternating Al2O3 and TiO2 cycles. The Ti content of the films showed a gradual increase as the number of TiO2 subcycles increased. The permittivity and refractive index gradually increased and the breakdown fields of ATO films decreased as the Ti content increased. The film growth is strongly dependent on the surface material in the ALD process; thus, this effect was considered when inducing the film growth rates of Al2O3 and TiO2 on the surface of ATO films. The growth rates of Al2O3 and TiO2 were dependent on the Ti content in the ATO films. Because of the low adsorption rate of Al precursors on the surfaces of the TiO2 films compared to on that of the Al2O3 films, the growth rate of the Al2O3 films on the TiO2 films was much lower than that on the surfaces of the Al2O3 films. With volume concentrations and a simple formula related to the refractive index, the refractive index of the ATO films was induced, which was in good agreement with the experimental results. (c) 2007 The Electrochemical Society.