High Electron Mobility of Nb-Doped SrTiO₃ Films Stemming from Rod-Type Sr Vacancy Clusters

Abstract

Achieving high electron mobility in SrTiO₃ films is of significant interest, particularly in relation to technological applications such as oxide semiconductors, field-induced superconductors, and thermoelectric generators. One route to achieving high electron mobility is growth of high quality SrTiO₃ films with low defect concentrations. Another approach for mobility enhancement is applying a strain to the crystal. However, the maximum mobilities obtainable by these approaches are limited both by external and internal factors (currently available fabrication techniques, and maximum crystal strain, for example). In this paper, we demonstrate a unique crystal engineering approach to alter the strain in Nb-doped SrTiO₃ films based on the deliberate introduction of Sr vacancy clusters. Nb-doped SrTiO₃ films produced in this manner are found to exhibit remarkably enhanced electron mobilities (exceeding 53 000 cm² V^–1 s^–1). This method of defect engineering is expected to enable tuning and enhancement of electron mobilities not only in SrTiO₃ films, but also in thin films and bulk crystals of other perovskite-type materials