Photovoltaic characteristics of Ca3Co4O9/Nb-doped SrTiO3 heterojunction

Ca3Co4O9/Nb-SrTiO3 heterojunction with good rectifying behavior at room temperature was fabricated by growing a layer of Ca3Co4O9 film on the 1wt% Nb-doped SrTiO3 substrate by means of the chemical solution deposition technique.A large open-circuit voltage signal with the response time of tens of nanosecond was observed at room temperature when the Ca3Co4O9 layer of the heterojunction was illuminated under the 308 nm irradiation and no voltage signal was detected under the 10.6 μm irradiation.A mechanism based on the photovoltaic effect of a p-n junction was proposed to explain the experimental results.The present work shows a great potential of this new heterojunction as photoelectric devices.