Effects of the flux-controlled cation off-stoichiometry in SrRuO_3 grown by molecular beam epitaxy on its physical and electrical properties

摘要

The SrRuO3 (SRO) thin films were epitaxially grown on (001) SrTiO3 (STO) substrates using plasma assisted molecular beam epitaxy (MBE). In order to identify how the cation flux affects the surface characteristics, films were grown at different Sr/Ru flux ratios. As Ru flux increased, SRO thin film exhibited a flatter but more bunched stepped terrace implying the prevalence of 2-D growth mode during the film formation, whereas excessive Sr flux led to 3-D film growth and resulted in a rough surface. In addition, XRD and STEM analysis provided that samples grown at Sr/Ru flux ratio higher than 2.7 showed volume expansion and crystal disorder by Ru vacancy which caused higher resistivity. But the samples grown at the ratio lower than 2.9 maintained the resistivity close to that of stoichiometric SRO. (C) 2020 Elsevier B.V. All rights reserved.