Electrical transport in passivated Pt/TiO₂/Ti Schottky diodes

Pt/TiO₂/Ti Schottky diodes were investigated by current-voltage analysis, photoresponse, and transient photocurrent (PC) in a wide temperature range. The compact TiO₂ as well as the SiO₂ passivation layers were prepared by the sol-gel technique. The Schottky-barrier height (1.2–1.3 eV) was equal to the difference of the work functions of Pt and Ti. The temperature dependence of the ideality factor was interpreted in terms of a Gaussian distribution of barrier heights [J. H. Werner and H. H. Güttler, J. Appl. Phys. 69, 1522 (1991)]. Space-charge-limited currents under the presence of defects with an exponential distribution were observed. Under zero-potential condition, the PC transients were practically independent of temperature and the electron drift mobility amounted to 2×10^-4 cm²/(V s). A screening dipole layer at the Pt/TiO₂ junction was formed under low forward and reverse potentials. Defects were generated under electron injection.