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arXiv · 2204.06823

Self-organised quantum dots in marginally twisted MoSe$_2$/WSe$_2$ and MoS$_2$/WS$_2$ bilayers

V. V. Enaldiev·F. Ferreira·J. G. McHugh·V. I. Fal'ko
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Abstract

Moir\'e superlattices in twistronic heterostructures are a powerful tool for materials engineering. In marginally twisted (small misalignment angle, $\theta$) bilayers of nearly lattice-matched two-dimensional (2D) crystals moir\'e patterns take the form of domains of commensurate stacking, separated by a network of domain walls (NoDW) with strain hot spots at the NoDW nodes. Here, we show that, for type-II transition metal dichalcogenide bilayers MoX$_2$/WX$_2$ (X=S, Se), the hydrostatic strain component in these hot spots creates quantum dots for electrons and holes. We investigate the electron/hole states bound by such objects, discussing their manifestations via the intralayer intraband infrared transitions. The electron/hole confinement, which is strongest for $\theta<0.5^{\circ}$, leads to a red-shift of their recombination line producing single photon emitters (SPE) broadly tuneable around 1\,eV by misalignment angle. These self-organised dots can form in bilayers with both aligned and inverted MoX$_2$ and WX$_2$ unit cells, emitting photons with different polarizations. We also find that the hot spots of strain reduce the intralayer MoX$_2$ A-exciton energy, enabling selective population of the quantum dot states.

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V. V. Enaldiev, F. Ferreira, J. G. McHugh, V. I. Fal'ko. 2022-04-14. Self-organised quantum dots in marginally twisted MoSe$_2$/WSe$_2$ and MoS$_2$/WS$_2$ bilayers. https://doi.org/10.1038/s41699-022-00346-0

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