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arXiv · 2011.09103

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

Kaoru Hisama·Mina Maruyama·Shohei Chiashi·Shigeo Maruyama·Susumu Okada
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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 $k = 2π/3$. 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 $Γ$ point in small diameter NTs, which is caused by the tensile strain resulting from their tubular structures.

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Kaoru Hisama, Mina Maruyama, Shohei Chiashi, Shigeo Maruyama, Susumu Okada. 2020-11-18. Indirect-to-direct band gap crossover of single walled MoS$_2$ nanotubes. https://doi.org/10.35848/1347-4065%2Fabffc6

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