Indirect-to-direct band gap crossover of single walled MoS${}_2$ nanotubes

Abstract

Using density functional theory, the electronic structures of single walled molybdenum disulfide nanotubes (MoS${}_2$ NTs) were investigated as a function of diameter. Our calculations show that the electronic structure near the band gap is sensitive to the NT diameter: armchair MoS${}_2$ NTs act as indirect gap semiconductors for diameters up to approximately 5.0 nm, while armchair MoS${}_2$ NTs with larger diameters act as direct gap semiconductors with band edges located in the vicinity of $k=2\pi /3$. This finding implies that MoS${}_2$ NTs with large diameters should exhibit similar photoluminescence to 2D monolayer MoS${}_2$ sheets. This indirect-to-direct band gap crossover is ascribed to the upward shift of the valence band peak at the $\Gamma$ point in small diameter NTs, which is caused by the tensile strain resulting from their tubular structures.

arXiv comment4 pages, 4 figures, under review

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Cited by in corpus (2)

• Photoluminescence from Single-Walled MoS${}_2$ Nanotubes Coaxially Grown on Boron Nitride Nanotubes
• Curvature-Controlled Band Alignment Transitions in 1D van der Waals Heterostructures