Continuously Tuning Epitaxial Strains by Thermal Mismatch

Lei Zhang, Yakun Yuan, Jason Lapano, Matthew Brahlek, Shiming Lei, Bernd Kabius, Venkatraman Gopalan, Roman Engel-Herbert

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Strain engineering of thin films is a conventionally employed approach to enhance material properties and to energetically prefer ground states that would otherwise not be attainable. Controlling strain states in perovskite oxide thin films is usually accomplished through coherent epitaxy by using lattice-mismatched substrates with similar crystal structures. However, the limited choice of suitable oxide substrates makes certain strain states experimentally inaccessible and a continuous tuning impossible. Here, we report a strategy to continuously tune epitaxial strains in perovskite films grown on Si(001) by utilizing the large difference of thermal expansion coefficients between the film and the substrate. By establishing an adsorption-controlled growth window for SrTiO3 thin films on Si using hybrid molecular beam epitaxy, the magnitude of strain can be solely attributed to thermal expansion mismatch, which only depends on the difference between growth and room temperature. Second-harmonic generation measurements revealed that structure properties of SrTiO3 films could be tuned by this method using films with different strain states. Our work provides a strategy to generate continuous strain states in oxide/semiconductor pseudomorphic buffer structures that could help achieve desired material functionalities.

Original languageEnglish (US)
Pages (from-to)1306-1312
Number of pages7
JournalACS nano
Volume12
Issue number2
DOIs
StatePublished - Feb 27 2018

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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    Zhang, L., Yuan, Y., Lapano, J., Brahlek, M., Lei, S., Kabius, B., Gopalan, V., & Engel-Herbert, R. (2018). Continuously Tuning Epitaxial Strains by Thermal Mismatch. ACS nano, 12(2), 1306-1312. https://doi.org/10.1021/acsnano.7b07539