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

Abstract

Moiré 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 moiré 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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• Moiré Superstructures in Marginally-Twisted NbSe${}_2$ Bilayers
• Moiré Band Engineering in Twisted Trilayer WSe2
• Stability of Wigner crystals and Mott insulators in twisted moiré structures
• Theory of interlayer exciton dynamics in 2D TMDCs Heterolayers under the influence of strain reconstruction and disorder
• Super Moiré Domain Tessellations, Sliding Ferroelectricity, and Reconfigurable Quantum Dot Arrays in Twisted Trilayer Hexagonal Boron Nitride