Effect of substrate temperature and RF biasing on the optical properties of titania-like thin films obtained by plasma enhanced chemical vapor deposition

Abstract

A low pressure radio frequency (RF) discharge (200 W) was operated in argon/oxygen with small admixtures of titanium(IV)isopropoxide (TTIP). By regulating the cooling temperature of the RF driven electrode, the influence of the substrate temperature and of the ion bombardment caused by the negative DC self-bias of the RF electrode was investigated comparatively. Thin titania-like films were obtained and characterized with respect to their cut-off wavelength and their spectral absorption coefficient in the UV range. Accordingly, the cut-off wavelength was found to be higher for films obtained on the DC-self-biased electrode. Here, its value appears independent of the substrate temperature and attained successively its maximum at 340 nm with deposition time. Furthermore, the absorption coefficients of films deposited on the DC self-biased electrode are well superior to those obtained on the grounded substrate holder. © 2009 WILEY-VCH Verlag GmbH & Co. KCaA, Weinheim.