Electrical conduction mechanism in polycrystalline titanium oxide thin films

Titanium oxide thin films were deposited onto glass substrates by a d.c. reactive sputtering technique. The temperature dependence of the electrical conductivity was studied using surface type cells, in a wide temperature range (120 K–570 K). The experiments showed that, after a heat treatment within the high temperature range 300 K–570 K, the temperature dependence of the electrical conductivity became reversible. The structural analysis of the heat-treated films indicated a polycrystalline anatase or/and rutile structure. The mechanism of the electronic transport in the studied samples was explained by applying models elaborated for films with polycrystalline (discrete) structure. Some characteristic parameters of these models were calculated: the energy barrier, EB = (0.046–0.082) eV and the constant interface-state distribution, NSS = (3.02 × 1012–1.23 × 1013) cm− 2 eV− 1.