Anisotropic Terahertz Emission from Bi2Se3 Thin Films with Inclined Crystal Planes

Sun Young Hamh, Soon Hee Park, Jeongwoo Han, Jeong Heum Jeon, Se Jong Kahng, Sung Kim, Suk Ho Choi, Namrata Bansal, Seongshik Oh, Joonbum Park, Jun Sung Kim, Jae Myung Kim, Do Young Noh, Jong Seok Lee

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3 Scopus citations

Abstract

We investigate the surface states of topological insulator (TI) Bi2Se3 thin films grown on Si nanocrystals and Al2O3 substrates by using terahertz (THz) emission spectroscopy. Compared to bulk crystalline Bi2Te2Se, film TIs exhibit distinct behaviors in the phase and amplitude of emitted THz radiation. In particular, Bi2Se3 grown on Al2O3 shows an anisotropic response with a strong modulation of the THz signal in its phase. From x-ray diffraction, we find that the crystal plane of the Bi2Se3 films is inclined with respect to the plane of the Al2O3 substrate by about 0.27°. This structural anisotropy affects the dynamics of photocarriers and hence leads to the observed anisotropic response in the THz emission. Such relevance demonstrates that THz emission spectroscopy can be a sensitive tool to investigate the fine details of the surface crystallography and electrostatics of thin film TIs.

Original languageEnglish (US)
Article number489
Pages (from-to)1-6
Number of pages6
JournalNanoscale Research Letters
Volume10
Issue number1
DOIs
StatePublished - Dec 1 2015

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics

Keywords

  • BiSe
  • Terahertz emission
  • Thin film
  • Topological insulator

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    Hamh, S. Y., Park, S. H., Han, J., Jeon, J. H., Kahng, S. J., Kim, S., Choi, S. H., Bansal, N., Oh, S., Park, J., Kim, J. S., Kim, J. M., Noh, D. Y., & Lee, J. S. (2015). Anisotropic Terahertz Emission from Bi2Se3 Thin Films with Inclined Crystal Planes. Nanoscale Research Letters, 10(1), 1-6. [489]. https://doi.org/10.1186/s11671-015-1190-y