High electrical conduction of Sb square net in anti-ThCr$_2$Si$_2$ type La$_2$O$_2$Sb thin film grown by multilayer solid-phase epitaxy

TL;DR

This study reports the first synthesis of La₂O₂Sb epitaxial thin films exhibiting high electrical conduction, significantly surpassing bulk polycrystals, due to enhanced carrier mobility and suppressed Sb dimerization.

Contribution

First successful growth of La₂O₂Sb epitaxial thin films with high electrical conduction using multilayer solid-phase epitaxy.

Findings

La₂O₂Sb thin films have an indirect band gap of 0.17 eV.

Resistivity at room temperature is about 10,000 times lower than bulk polycrystals.

High conduction attributed to increased carrier mobility from suppressed Sb dimerization.

Abstract

Anti-ThCr$_2$Si$_2$ type $RE_2$O$_2$Sb ($RE$ = rare earth) with Sb square net has shown insulating conduction so far. Here we report the synthesis of La$_2$O$_2$Sb 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 La$_2$O$_2$Sb 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 La$_2$O$_2$Sb bulk polycrystal, attributed to increased carrier mobility probably due to suppressed Sb dimerization.