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Adsorption-Controlled Growth of SrTiO<sub>3</sub> by Oxide Molecular-Beam Epitaxy

ORAL

Abstract

Strontium titanate (SrTiO3) is an exciting model system with properties that can emerge or be suppressed through small perturbations, including non-stoichiometry. Historically, growing high-quality SrTiO3 thin films by molecular-beam epitaxy (MBE) has been challenging due to the precise calibration required. It would be useful if there were a thermodynamic regime where the composition of SrTiO3 was self regulating. At high temperatures, the volatility of Sr-containing species from SrTiO3 exceeds that of Ti-containing species; this suggests that adsorption-controlled growth may be possible for SrTiO3 without the use of a metalorganic precursor.

We show that the growth window for adsorption-controlled SrTiO3, using conventional elemental MBE precursors, is from approx. 1450-1475 ℃ with an Sr:Ti incident flux ratio of 5:1. An advantage of this high temperature regime, nearly 75% of the homologous temperature of SrTiO3, is that misfit dislocations may react with each other resulting in a grid of misfit dislocations near the substrate/film interface and a relatively low density of threading dislocations in the SrTiO3 epitaxial film. For example, we estimate an upper bound on the threading dislocation density of our SrTiO3 films on LaAlO3 (001) to be 2x107 cm-2. X-ray diffraction, atomic force microscopy, S/TEM, ultraviolet Raman spectroscopy, and thermal conductivity data will be presented.

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Presenters

  • Dylan Sotir

    Cornell University, Department of Materials Science and Engineering, Cornell University

Authors

  • Dylan Sotir

    Cornell University, Department of Materials Science and Engineering, Cornell University

  • Matthew R Barone

    Department of Materials Science and Engineering, Cornell University, Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University

  • Francisco Guzman

    Department of Materials Science and Engineering, University of California Irvine

  • Chaojie Du

    Department of Materials Science and Engineering, University of California Irvine

  • Benjamin Z Gregory

    Cornell University, Department of Physics, Cornell University

  • Amelia Schaeffer

    School of Applied and Engineering Physics, Cornell University

  • Viviana Glick

    Department of Chemistry, Haverford College

  • Yorick Birkholzer

    Cornell University, Department of Materials Science and Engineering, Cornell University

  • ShunLi Shang

    Department of Materials Science and Engineering, The Pennsylvania State University

  • Andrej Singer

    Cornell University, Department of Materials Science and Engineering, Cornell University

  • Zhiting Tian

    Sibley School of Mechanical and Aerospace Engineering, Cornell University

  • Zi-Kui Liu

    Department of Materials Science and Engineering, The Pennsylvania State University

  • Dmitri A Tenne

    Boise State University

  • Xiaoqing Pan

    University of California, Irvine, Department of Materials Science and Engineering, University of California Irvine

  • Darrell G Schlom

    Cornell University, Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University