Structure and phase composition of thin TiO2 films grown on the surface of metallized track-etched polyethylene terephthalate membranes by reactive magnetron sputtering

Abstract

We have studied TiO₂, Ag, Ag/TiO₂, and Cu/TiO₂ coatings grown on track-etched polyethylene terephthalate membranes. The metals and oxides were deposited by reactive vacuum sputtering using a planar magnetron. The microstructure of the samples were examined by scanning and transmission electron microscopy techniques. The elemental composition of the coatings were determined by energy dispersive X-ray microanalysis, and their phase composition was determined by X-ray diffraction at different temperatures and by transmission electron diffraction. Titanium dioxide can be present on the surface of track-etched membranes (TMs) in three forms: nanocrystals of tetragonal anatase with orthorhombic brookite and amorphous TiO₂ impurities. The copper-metallized TM has been shown to contain cubic Cu₂O. The optical properties of the composite membranes and films have been studied by absorption spectroscopy. The energies of direct and indirect allowed optical transitions have been evaluated from measured absorption spectra of the TiO₂, Ag/TiO₂, and Cu/TiO₂ coatings.