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The direct-to-indirect band gap crossover in two-dimensional van der Waals Indium Selenide crystals


G.W. Mudd

M.R. Molas

X. Chen


K. Nogajewski

Zakhar D. Kovalyuk

G. Yusa

M. Potemski

V.I. Fal'ko


The electronic band structure of van der Waals (vdW) layered crystals has properties that depend on the composition, thickness and stacking of the component layers. Here we use density functional theory and high field magneto-optics to investigate the metal chalcogenide InSe, a recent addition to the family of vdW layered crystals, which transforms from a direct to an indirect band gap semiconductor as the number of layers is reduced. We investigate this direct-to-indirect bandgap crossover, demonstrate a highly tuneable optical response from the near infrared to the visible spectrum with decreasing layer thickness down to 2 layers, and report quantum dot-like optical emissions distributed over a wide range of energy. Our analysis also indicates that electron and exciton effective masses are weakly dependent on the layer thickness and are significantly smaller than in other vdW crystals. These properties are unprecedented within the large family of vdW crystals and demonstrates the potential of InSe for electronic and photonic technologies.


Mudd, G., Molas, M., Chen, X., Zólyomi, V., Nogajewski, K., Kudrynskyi, Z. R., …Patanè, A. (2016). The direct-to-indirect band gap crossover in two-dimensional van der Waals Indium Selenide crystals. Scientific Reports, 6(1), Article 39619.

Journal Article Type Article
Acceptance Date Nov 23, 2016
Online Publication Date Dec 23, 2016
Publication Date 2016-12
Deposit Date Jan 3, 2017
Publicly Available Date Jan 3, 2017
Journal Scientific Reports
Electronic ISSN 2045-2322
Publisher Nature Publishing Group
Peer Reviewed Peer Reviewed
Volume 6
Issue 1
Article Number 39619
Public URL
Publisher URL
Related Public URLs


srep39619.pdf (1.9 Mb)

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