Pt ∕ Ti O 2 ∕ 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 (1.2–1.3eV) 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 2×10−4cm2∕(Vs). A screening dipole layer at the Pt∕TiO2 junction was formed under low forward and reverse potentials. Defects were generated under electron injection.

Electrical properties of two kinds of sandwich structures (SnO 2 : F/por-TiO 2 /Ti and Si/por-TiO 2 /Pd) are investigated by the methods of I-V, C-V characteristics and DLTS in vapors of water and alcohol. It has been demonstrated that besides the change of the conductivity and of the capacitance of the por-TiO 2 layers one can also use for gas sensing the change of the high frequency capacitance of the MOS type structure, measurement of the current response at relatively low frequencies and the modification of the charge transfer between the Si bulk and states near the por-TiO 2 /Si interface.

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The behaviour of localized states in Pd/nano-or mesoporous Si/p-Si heterojunctions is studied by the DLTS technique in a vacuum and different atmospheres: ambient air, Ar, N 2 , CO 2 , O 2 . The complex DLTS spectra of both signs related to electron and hole traps in porous Si are detected. The intensity of DLTS peaks and activation energy is shown to be dependent on the morphology of the porous layers and ambient atmosphere in which DLTS measurements were carried out. The shift of activation energy with increase of the applied reverse voltage is interpreted from the point of view of a spatially inhomogeneous distribution of localized states in a porous layer. The cyclic transformation of DLTS spectra is observed for consecutive measurements in a vacuum and ambient atmosphere. Oxygen adsorption (at partial pressure of a few mbar) results in strong passivation of deep traps in mesoporous Si.