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Electrical conductivity and Hall-effect measurements on undoped and Sb-doped SnO 2 thin films prepared by the sol-gel technique were carried out as a function of temperature (55 K to 300 K). Structural characterizations of the films were performed by atomic force microscopy (AFM) and x-ray diffraction (XRD). A doping-induced metal-insulator transition (MIT) was observed. On the metallic side of the transition, the experimental data were interpreted in terms of electron-electron interactions (EEI). The existence of EEI was confirmed by excellent agreement between theoretical and experimental data. The experimental data on the insulator side of the transition were analyzed in terms of variable-range hopping (VRH) conduction. A complete set of parameters describing the properties of the localized electrons, including hopping energy, hopping distance, and the value of the density of states at the Fermi level, was determined.

Cu2O thin films were chemically deposited on single-crystal p-Si substrates to form Cu2O/p-Si heterojunctions. The structure of the Cu2O films was analysed by x-ray diffraction spectroscopy and UV–Vis–NIR transmittance spectra. In order to investigate the dark current transport mechanism in Cu2O/p-Si heterojunctions the current–voltage characteristics were measured in the temperature range 120–320 K and capacitance–voltage characteristics at a high frequency of ∼1 MHz at room temperature. The I–V–T characteristics revealed that the forward current was determined by trap-assisted multi-step tunnelling. The activation energy determined from the saturation current and the junction built-in potential determined from the capacitance–voltage characteristics were about 0.18 eV and 1.10 V at room temperature, respectively.