First principles study of the band gaps and edges of (111) epitaxially strained SrTiO$_3$

ORAL

Abstract

SrTiO$_3$ is a tunable material with potential use in energy applications. Previous experimental and first principles results demonstrated controllable manipulation of the electronic band gap in (001) biaxially strain, and predicted a large room-temperature band gap reduction (0.3 eV) for (111) epitaxial growth at small and large strains. In this work, we revisit and examine the effect of (111) epitaxial strain on the structural and electronic properties of SrTiO$_3$ using density functional theory calculations at low and room temperatures. Under (111) epitaxial strain at low temperature, we find that SrTiO$_3$ has an antiferrodistortive ground state at large compressive strains ($<$ -1\%) and a ferroelectric phase transition between -1\% $<$ $\eta$ $<$ 4\% biaxial strains. While structural distortions widen the band gap compared to the paraelectric phase, an effective reduction of band gap is observed for the distorted structure at large compressive strains compared to bulk. This work is supported by DOE, computational resources are provided by NERSC.

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Authors

  • Sebastian E. Reyes-Lillo

    Molecular Foundry, Lawrence Berkeley National Laboratory

  • Robert F. Berger

    Department of Chemistry, Western Washington University

  • Jeffrey Neaton

    Univ of California - Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory, Physics Department, UC Berkeley \& Molecular Foundry, LBNL \& Kavli Energy NanoSciences Institute at Berkeley, Berkeley, University of California at Berkeley, University of California, Berkeley; Lawrence Berkeley National Laboratory, Dept. of Physics, UC Berkeley, Molecular Foundry, Lawrence Berkeley National Laboratory; Department of Physics, University of California-Berkeley, University of California, Berkeley and Lawrence Berkeley National Lab, Molecular Foundry, Lawrence Berkeley National Laboratory, and Department of Physics, UC-Berkeley, Lawrence Berkeley National Laboratory