Adjusting the photoconductive properties of LaCoO3 thin films by epitaxial strain

Abstract

Epitaxial strained LaCoO 3 thin films with (001) orientation were prepared on various substrates, i.e., LaAlO 3 , SrTiO 3 and LaSrAlO 4 , respectively, by polymer assisted deposition. Owing to lattice mismatch, different lattice strain and tetragonal distortion of the oxygen octahedra exist in the obtained LaCoO 3 films. These films exhibit excellent visible-light photoconductive performance. It reveals that the tetragonal distortion of CoO 6 octahedra results in a decrease of Δ CF as well as E g , enhancing the photoconductive performance of LaCoO 3 thin films. A relatively high degree of the tetragonal distortion corresponds to higher photocurrent of the films, and the tetragonal distortion as well as photoconductive properties can be “adjusted” by epitaxial strain introduced in the LaCoO 3 thin films. The adjusting method by epitaxial strain developed in this study provides a viable way for developing high-performance perovskite photoconductive semiconductor and can be extended to other optoelectronic systems. • The photoconductivity properties of LaCoO 3 films can be adjusted by epitaxial strain. • Larger tetragonal distortion of [CoO 6 ] corresponds to higher photocurrent. • The adjusting method can be extended to other optoelectronic systems.