Structural distortion and photoconductive modulation of La1-xYxCoO3 epitaxial films

In this work, we successfully prepared epitaxial La1-xYxCoO3 (x = 0, 0.05, 0.1, 0.15) films on (100) SrTiO3 by polymer assisted deposition. The synergistic effect of biaxially tensile strain and doping yttrium on the structural distortion and photoconductive process of the films has been investigated. Due to lattice mismatch, the epitaxial strain along c-axis as well as the strain-induced tetragonal distortion of La1-xYxCoO3 films increase with the content of doping yttrium. As-prepared films have higher degree of CoO6 octahedral distortion, i.e., Jahn-Teller like tetragonal distortion, which result in lower crystal field splitting energy and narrower band gap energy, thereby elevating the charge transition. Additionally, increase of epitaxial strain leads to lower adsorption free energy in La1-xYxCoO3 films, and results in the increase of chemisorbed oxygen, which is beneficial to electron transport in the process of light response. The introduction of new oxygen vacancy defect sites by doping Y3+ ions and the proper amount of oxygen vacancy can effectively inhibit the recombination of the photo-induced electron-hole pairs, thus improving the activity for photoconductive response. The results reveal that the photoconductive properties of the as-prepared films are largely related to the synergistic effect of biaxially tensile-strained tetragonal distortion of CoO6 and doping yttrium.

Automated summary

This study investigated the structural distortion and photoconductive process of La1-xYxCoO3 films, revealing that factors such as lattice mismatch and octahedral distortion contribute to the superior photoconductive properties of the films.