Analysis of surface properties of semiconducting (Ti,Pd,Eu)O-x thin films

摘要

In this paper an analysis of the surface properties of (Ti, Pd, Eu)Ox thin films prepared by magnetron sputtering has been described. In particular, the results of composition and structure investigations were studied in relation to the surface state and optical properties. It was found that (Ti, Pd, Eu) Ox film was nanocrystalline and had a rutile structure. The average crystallites size was equal to 7.8 nm. Films were homogeneous and had densely packed grains. Investigation of the surface properties by XPS showed that titanium was present at 4+ state (in the TiO2 form), palladium occurred as PdO2 (also at 4+ state), while europium was in Eu2O3 form (at 3+ state). In comparison with the unmodiffied TiO2, the coating with Pd and Eu additives had a rather high transparency (approx. 47%) in the visible light range, its optical absorption edge was shifted towards into the longer wavelengths (from 345 nm to 452 nm), and the width of optical energy gap Egopt was nearly twice lower (1.82 eV). Besides, the resistivity of (Ti, Pd, Eu) Ox at room temperature was 1x10(3) Wcm. In the case of the film as-deposited on Si substrate (p-type) the generation of photocurrent as a response to light beam excitation (lambda(exc) = 527 nm) was observed.