Thickness dependence of the optical properties of sputter deposited Ti oxide films

Amorphous and crystalline Ti oxide films were obtained by reactive magnetro n sputtering onto substrates at different temperatures. Optical constants o f the films were determined from spectrophotometric measurements of reflect ance and transmittance. The amorphous films had a band gap of similar to 3. 4 eV and a wide absorption tail extending to lower energies. The crystallin e films displayed a band gap of 3.3-3.35 eV and a more narrow absorption ta il. The optical constants were dependent on film thickness. The crystalline films showed evidence of structural inhomogeneities leading to diffuse sca ttering in the thicker films as well as to a grading of the refractive inde x. (C) 2000 Elsevier Science S.A. All rights reserved.