Novel visible-light-driven photoconductive properties of LaCoO3 epitaxial nano-thin films

Abstract

LaCoO3 nano-thin films were grown on (001), (110) and (111) oriented SrTiO3 substrates by the polymer assisted deposition method, respectively. All the LaCoO3 films are in epitaxial growth in accordance with the orientation of STO, with biaxial tensile strain. The films, especially for (111) oriented film, exhibit excellent visible-light photoconductive properties. The strain-induced increase of Co-O bond length may contribute to reduce the t2g-eg gap of Co3+ and further increase the number of photoexcited eg itinerant electrons. The different photoconductive activity of LaCoO3 epitaxial films may be attributed to the different surface energies of crystal planes. It suggests that the LaCoO3 epitaxial film can be considered as a potential candidate for visible-light photodetector.