Characterization of Rotational Stacking Layers in Large-Area MoSe2 Film Grown by Molecular Beam Epitaxy and Interaction with Photon

Yoon Ho Choi, Dong Hyeok Lim, Jae Hun Jeong, Dambi Park, Kwang Sik Jeong, Minju Kim, Aeran Song, Hee Suk Chung, Kwun Bum Chung, Yeonjin Yi, Mann Ho Cho

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Transition metal dichalcogenides (TMDCs) are promising next-generation materials for optoelectronic devices because, at subnanometer thicknesses, they have a transparency, flexibility, and band gap in the near-infrared to visible light range. In this study, we examined continuous, large-area MoSe2 film, grown by molecular beam epitaxy on an amorphous SiO2/Si substrate, which facilitated direct device fabrication without exfoliation. Spectroscopic measurements were implemented to verify the formation of a homogeneous MoSe2 film by performing mapping on the micrometer scale and measurements at multiple positions. The crystalline structure of the film showed hexagonal (2H) rotationally stacked layers. The local strain at the grain boundaries was mapped using a geometric phase analysis, which showed a higher strain for a 30° twist angle compared to a 13° angle. Furthermore, the photon-matter interaction for the rotational stacking structures was investigated as a function of the number of layers using spectroscopic ellipsometry. The optical band gap for the grown MoSe2 was in the near-infrared range, 1.24-1.39 eV. As the film thickness increased, the band gap energy decreased. The atomically controlled thin MoSe2 showed promise for application to nanoelectronics, photodetectors, light emitting diodes, and valleytronics.

Original languageEnglish
Pages (from-to)30786-30796
Number of pages11
JournalACS Applied Materials and Interfaces
Volume9
Issue number36
DOIs
StatePublished - 13 Sep 2017

Keywords

  • dielectric dispersion
  • localized strain
  • molecular beam epitaxy
  • molybenum diselenides
  • optical band gap
  • rotational layer
  • transition metal dichalcogenids

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