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

doi:10.1039/C3NR06072A

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

Ning Lu,‡^ab Hongyan Guo,‡^bc Lei Li,^b Jun Dai,^b Lu Wang,^cd Wai-Ning Mei,^d Xiaojun Wu*^ce and Xiao Cheng Zeng*^be

Author affiliations

* Corresponding authors

^a Department of Physics, Anhui Normal University, Wuhu, Anhui, China

^b Department of Chemistry and Department Mechanics and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
E-mail: xzeng1@unl.edu

^c CAS Key Lab of Materials for Energy Conversion, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China
E-mail: xjwu@ustc.edu.cn

^d Department of Physics, University of Nebraska-Omaha, Omaha, NE 68182, USA

^e Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026, China

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 WSe₂/MoS₂ heterobilayer which retains the direct-bandgap character of the constituent monolayer. For M = Fe, V; X = S, Se, the MX₂/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.

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DOI: https://doi.org/10.1039/C3NR06072A
Article type: Paper
Submitted: 15 Nov 2013
Accepted: 09 Dec 2013
First published: 19 Dec 2013
This article is Open Access

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Nanoscale, 2014,6, 2879-2886

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

N. Lu, H. Guo, L. Li, J. Dai, L. Wang, W. Mei, X. Wu and X. C. Zeng, Nanoscale, 2014, 6, 2879 DOI: 10.1039/C3NR06072A

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