Electrical and optical properties of (Ta2O5)1−x-(TiO2)x films, x = 0.035, prepared by sputtering of ceramic and mosaic (Ta, Ti) metal targets

Abstract

(Ta2O5)1−x-(TiO2)x, with x = 0.035, thin films were deposited onto p-type silicon and quartz substrates following two different routes: first, by the sputtering of the ceramic target and, second, by sputtering of mosaic (Ta, Ti) metal target in the presence of oxygen (hereafter referred to as CT and MT, respectively). The deposited films were found to crystallize on annealing at and above 700 °C. The dielectric constant of the prepared films was found to increase with increasing annealing temperature, up to 700 °C, and on annealing at 800 °C, it was found to decrease. The dielectric constant of the CT was observed to be higher than that of the MT film structures at each annealing temperature. From the transmittance measurements, different optical parameters of the deposited crystalline films were calculated. The leakage current density of the CT films was found to increase with the annealing temperature, whereas in the MT films, it drastically decreased by an order of ∼3 when the annealing temperature was increased from 700 to 800 °C. Different conduction mechanisms were observed in the different applied field regions in the prepared film structure. The observed electrical properties of the prepared film structure seem to depend on the status of the growing interfacial oxide layer on annealing.