Highly c-axis-oriented polycrystalline LiNbO3 films on Si(001) substrates were prepared by the radio-frequency magnetron sputtering process. Measurements of the fundamental absorption edge indicated that the optical band gap corresponds to direct and indirect transitions with energies E-g(dir) = 42 eV and E-g(ind) = 22 eV, respectively. Analysis of the Rutherford backscattering data suggested that Li atoms penetrate into silicon substrate forming inhomogeneous donor distribution. Based on the analysis of current-voltage and capacitance-voltage characteristics, the band diagram of the Si-LiNbO3 heterojunction was proposed. It was demonstrated that charge transport is affected by the barrier's properties at the heterojunction and it can be described in the framework of the Richardson-Schottky emission and Fowler-Nordheim tunneling. (C) 2013 Elsevier B.V. All rights reserved.