MoS2/MX2 heterobilayers: Bandgap engineering via tensile strain or external electrical field

Ning Lu, Hongyan Guo, Lei Li, Jun Dai, Lu Wang, Wai Ning Mei, Xiaojun Wu, Xiao Cheng Zeng

Research output: Contribution to journalArticle

218 Scopus citations

Abstract

We have performed a comprehensive first-principles study of the electronic and magnetic properties of two-dimensional (2D) transition-metal dichalcogenide (TMD) heterobilayers MX2/MoS2 (M = Mo, Cr, W, Fe, V; X = S, Se). For M = Mo, Cr, W; X = S, Se, all heterobilayers show semiconducting characteristics with an indirect bandgap with the exception of the WSe 2/MoS2 heterobilayer which retains the direct-bandgap character of the constituent monolayer. For M = Fe, V; X = S, Se, the MX 2/MoS2 heterobilayers exhibit metallic characters. Particular attention of this study has been focused on engineering the bandgap of the TMD heterobilayer materials via application of either a tensile strain or an external electric field. We find that with increasing either the biaxial or uniaxial tensile strain, the MX2/MoS2 (M = Mo, Cr, W; X = S, Se) heterobilayers can undergo a semiconductor-to-metal transition. For the WSe2/MoS2 heterobilayer, a direct-to-indirect bandgap transition may occur beyond a critical biaxial or uniaxial strain. For M (=Fe, V) and X (=S, Se), the magnetic moments of both metal and chalcogen atoms are enhanced when the MX2/MoS2 heterobilayers are under a biaxial tensile strain. Moreover, the bandgap of MX2/MoS2 (M = Mo, Cr, W; X = S, Se) heterobilayers can be reduced by the vertical electric field. For two heterobilayers MSe2/MoS2 (M = Mo, Cr), PBE calculations suggest that the indirect-to-direct bandgap transition may occur under an external electric field. The transition is attributed to the enhanced spontaneous polarization. The tunable bandgaps in general and possible indirect-direct bandgap transitions due to tensile strain or external electric field make the TMD heterobilayer materials a viable candidate for optoelectronic applications.

Original languageEnglish (US)
Pages (from-to)2879-2886
Number of pages8
JournalNanoscale
Volume6
Issue number5
DOIs
StatePublished - Mar 7 2014

ASJC Scopus subject areas

  • Materials Science(all)

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