Strain effects in epitaxial La‐doped SrSnO 3 films on lattice‐matched PMN‐PT substrates

Abstract Here we report the effect of the strain states on the structure, optical and electrical transport properties of the La 0.05 Sr 0.95 SnO 3 (LSSO) thin films grown epitaxially on (001)‐oriented 0.70 Pb(Mg 1/3 Nb 2/3 )O 3 ‐0.30PbTiO 3 (PMN‐PT) substrates by pulsed laser deposition. X‐ray diffraction results indicate that the films are fully strained up to at least 100 nm thickness, and the in‐plane compressive strain gradually releases in thicker films. High‐resolution transmission electron microscopy characterizations demonstrate that the LSSO films were grown coherently on PMN‐PT(001) substrates. With varying the thicknesses of the fully strained films from 20 to 100 nm, the electrical transport properties are improved significantly. A lowest room‐temperature resistivity of 1.88 mΩcm and the highest mobility of 28.1 cm 2 /Vs are obtained in the 100 nm film. The optical band gap determined from spectroscopic ellipsometry is found to increase from 4.58 to 4.88 eV with the film thicknesses varying from 20 to 500 nm. The results imply that the LSSO epitaxial films exhibit tunable electrical performances and optical band gaps through strain, which may have potential applications in optoelectrical devices.