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Open Access Publications from the University of California

Possible electric field induced indirect to direct band gap transition in MoSe2

  • Author(s): Kim, BS
  • Kyung, WS
  • Seo, JJ
  • Kwon, JY
  • Denlinger, JD
  • Kim, C
  • Park, SR
  • et al.

© 2017 The Author(s). Direct band-gap semiconductors play the central role in optoelectronics. In this regard, monolayer (ML) MX2(M = Mo, W; X = S, Se) has drawn increasing attention due to its novel optoelectronic properties stemming from the direct band-gap and valley degeneracy. Unfortunately, the more practically usable bulk and multilayer MX2have indirect-gaps. It is thus highly desired to turn bulk and multilayer MX2into direct band-gap semiconductors by controlling external parameters. Here, we report angle-resolved photoemission spectroscopy (ARPES) results from Rb dosed MoSe2that suggest possibility for electric field induced indirect to direct band-gap transition in bulk MoSe2. The Rb concentration dependent data show detailed evolution of the band-gap, approaching a direct band-gap state. As ionized Rb layer on the surface provides a strong electric field perpendicular to the surface within a few surface layers of MoSe2, our data suggest that direct band-gap in MoSe2can be achieved if a strong electric field is applied, which is a step towards optoelectronic application of bulk materials.

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