Band diagram of the Si-LiNbO3 heterostructures grown by radio-frequency magnetron sputtering

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 Egdir = 4.2 eV and Egind = 2.2 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.