Microstructure and band gap modulation of SrSn1-xCoxO3 epitaxial thin films via pulsed laser deposition

Abstract

Perovskite-structured SrSnO3 has attracted considerable attention in recent years because of its unusual dielectric and semiconducting properties. Certain dopants can be used to modify and improve the properties of these materials. Epitaxial SrSn1-xCoxO3 (x = 0, 0.16, 0.33, 0.5) (SSCO) thin films were deposited on single crystal SrTiO3(001) substrates via the pulsed laser deposition method. The crystallinity, microstructure, optical, and electrical properties of the films were investigated. The results indicated that SrSn1-xCoxO3 films were epitaxially grown on SrTiO3(001) substrate with both a perovskite structure and high crystallinity irrespective of the Co doping level. The films exhibited a smooth and dense morphology with a root-mean-square roughness of 0.44 nm and a film thickness of ~200 nm. As the‘x’value increased from 0 to 0.5, the optical transmittance decreased from 90%to 25%, and the band gap dropped from 4.24 to 2.44 eV. Moreover, the doped film exhibited a high dielectric constant of 70.1 at 106 Hz, 57% higher than the control SrSnO3 film. The SSCO film displayed surface resistivity of 172 MΩ at room temperature and high stability at temperature up to 1000 °C.