Formation of SnO and SnO2 phases during the annealing of SnO(x) films obtained by molecular beam epitaxy

Alexander Nikiforov, Vyacheslav Timofeev, Vladimir Mashanov, Ivan Azarov, Ivan Loshkarev, Vladimir Volodin, Dmitry Gulyaev, Igor Chetyrin, Ilya Korolkov

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3 Citations (Scopus)

Abstract

SnO and SnO2 films were obtained on the SiO2 surface by the molecular-beam epitaxy method. The initial films are in the polycrystalline phase. The annealing of SnO(x) films at a temperature of 300 °C resulted in the formation of the tetragonal SnO phase. Three vibration modes Eg, A1g, and B1g with the frequencies of Sn[sbnd]O bond vibrations of 113, 211 and ~360 cm−1, respectively, which correspond to the SnO phase, were first observed by the Raman spectroscopy method. The orthorhombic SnO2 films were obtained by increasing the annealing temperature to 500 °C. Based on the valence band XPS (X-ray photoelectron spectroscopy) spectrum, several features with the binding energy approximately 5 eV, 7.5 eV and 11 eV, which are the same with the valence band of SnO2, were identified. The refractive index and absorption coefficient were investigated by the spectral ellipsometry technique. The high absorption coefficients correspond to the high Sn content. The film dielectric properties were revealed at the temperature higher than 300 °C. The refractive index values lie in the range of 1.5–2.6 for the visible spectral region. The pronounced absorption edges at 2.85 eV and 3.6 eV corresponding to those of stannous oxide (SnO) and stannic oxide (SnO2) were observed. The photoluminescence (PL) from the SnO(x) films was observed at room temperature. The increase of the annealing temperature resulted in the increase of PL intensity. Such PL intensity behavior is likely due to the Sn nanoislands.

Original languageEnglish
Article number145735
Number of pages7
JournalApplied Surface Science
Volume512
DOIs
Publication statusPublished - 15 May 2020

Keywords

  • Absorption edge
  • Molecular-beam epitaxy
  • Morphology
  • Photoluminescence
  • Raman spectroscopy
  • Refractive index
  • Tin oxide
  • X-ray phase analysis
  • X-ray photoelectron spectroscopy
  • THIN-FILMS
  • OXIDATION
  • DEPOSITION
  • ELECTRICAL-PROPERTIES
  • RAMAN-SCATTERING
  • EVAPORATION
  • GROWTH
  • TIN
  • OXIDES
  • QUARTZ

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