Photovoltaic effects and its oxygen content dependence in BaTiO3−δ∕Si heterojunctions

Three oxide heterojunctions made of BaTiO3−δ∕Si have been fabricated under various oxygen pressures by laser molecular beam epitaxy. They all exhibited nonlinear and rectifying I-V characteristics but with a large difference in the rectification behaviors. Their photoelectric properties and dependences on oxygen contents in BaTiO3−δ films have been experimentally studied. We found that the photovoltaic effects depended strongly on the oxygen contents of the BaTiO3−δ films. The possible mechanism was proposed based on the band structure of the p-n heterojunctions.