Polycrystalline titania and Nb:TiO2 thin films were deposited by RF magnetron sputtering. The influence of postdeposition
annealing in vacuum and hydrogen atmosphere on the structure, morphology, oxidation states and
optical properties was studied by X-ray diffraction, atomic force microscopy, XPS and UV–VIS spectroscopy.
The heat treatment of titaniumdioxide thin films in vacuumand H2 atmosphere induces structural and morphological
changes. The band gap narrowing was observed for the transparent as-deposited Nb:TiO2 films, while annealing
at 420 °C in H2 atmosphere resulted in an enhancement of the electrical conductivity. Further on, TiO2/p-
CdTe photovoltaic devices with efficiency of 1.8% were fabricated and their characteristic ‘enhancement’ is
discussed.