High electrical conduction of the Sb square net in an anti-ThCr2Si2 type La2O2Sb thin film grown by multilayer solid-phase epitaxy

Abstract

Anti-ThCr₂Si₂ type RE₂O₂Sb (RE = rare earth) with a Sb square net has shown insulating conduction so far. Here we report the synthesis of La₂O₂Sb epitaxial thin films for the first time by multilayer solid-phase epitaxy. The valence state of Sb was about −2 evaluated from X-ray photoemission spectroscopy measurement, and the indirect band gap of 0.17 eV was observed. The La₂O₂Sb epitaxial thin film showed unexpectedly high electrical conduction as a narrow gap semiconductor, whose resistivity at room temperature was approximately ten-thousand-fold lower than that of La₂O₂Sb bulk polycrystal, attributed to increased carrier mobility probably due to suppressed Sb dimerization.