On the structure, morphology and electrical conductivities of titanium oxide thin films

Titanium oxide thin films were prepared by a d.c. sputtering technique onto glass substrates. The morphology of the films was analysed by atomic force microscopy and their structure by X-ray diffraction. The structure and phase composition of the films depend on the deposition conditions. The small values for roughness obtained from AFM, ranging from 3 to 9 nm, show relatively smooth surfaces. Temperature dependences of the electrical conductivities were studied in a wide range, 13-560 K. The values of activation energies of electrical conduction, calculated from the temperature dependences of the electrical conductivity, varied between 0.13 and 0.39 eV, for temperature range 310-468 K. The current-voltage characteristics are ohmic for values of applied voltage lower than 0.5 V. For higher values, the mechanism of electrical conduction is determined by space-charge-limited currents.