Electrical and structural properties of reduced titanium dioxide thin films deposited by pulsed excimer laser ablation

Thin films of reduced titanium dioxide were deposited on Si and glass substrates by the pulsed excimer laser ablation technique at different hydrogen ambient pressures and substrate temperatures. At room temperature the resistivity of T i O2 reduced to about 17-18 orders at magnitude. Electrical conductivity of the films was studied in low temperature region up to 100 k. The average activatio ergies obtained are in the range of 0.008 to 0.160 eV with a change in the slope of the log σ Vs 1/T around the temperature of 180-200 K, except in the film deposited at a hydrogen pressure of 100 mtorr and substrate temperature of 400 C which is linear throughout the measured temperature range. X-ray diffraction patterns of the films showed that the films contained mixed t i-O phases. The electrical conductivity are found to strongly dependent on the degree of reduction, i.e. change in the composition of T i O2x