Temperature dependence of band gap in MoSe2 grown by molecular beam epitaxy

Byoung Ki Choi, Minu Kim, Kwang Hwan Jung, Jwasoon Kim, Kyu Sang Yu, Young Jun Chang

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Abstract

We report on a temperature-dependent band gap property of epitaxial MoSe2 ultrathin films. We prepare uniform MoSe2 films epitaxially grown on graphenized SiC substrates with controlled thicknesses by molecular beam epitaxy. Spectroscopic ellipsometry measurements upon heating sample in ultra-high vacuum showed temperature-dependent optical spectra between room temperature to 850 °C. We observed a gradual energy shift of optical band gap depending on the measurement temperature for different film thicknesses. Fitting with the vibronic model of Huang and Rhys indicates that the constant thermal expansion accounts for the steady decrease of band gap. We also directly probe both optical and stoichiometric changes across the decomposition temperature, which should be useful for developing high-temperature electronic devices and fabrication process with the similar metal chalcogenide films.

Original languageEnglish
Article number492
JournalNanoscale Research Letters
Volume12
DOIs
StatePublished - 2017

Keywords

  • MoSe
  • Molecular beam epitaxy
  • Spectroscopic ellipsometry
  • Temperature-dependent band gap
  • Thermal stability
  • Time of flight medium-energy ion-scattering spectroscopy

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