Self-organized quantum dots in reconstructed MoX₂/WX₂ heterostructures

Moiré superlattices in twisted bilayers of two-dimensional semiconductors have emerged as versatile tools for engineering quantum states of quasiparticles. Among the systems of particular interest are twistronic MoSe₂/WSe₂ and MoS₂/WS₂ heterostructures which feature type-II band alignment between monolayer conduction and valence bands. It was also noted that the interfaces of such same-chalcogen heterostructures undergo reconstruction into preferential stacking domains and highly strained domain wall networks which have a profound effect on the electron and hole localization across moiré superlattices. We present a catalogue of options for the formation of self-organized quantum dots and wires for electrons, holes and excitons in lattice-reconstructed marginally twisted MoSe₂/WSe₂ and MoS₂/WS₂ bilayers, which can be realized individually by fine tuning the twist angle between layers from perfect alignment to θ∽1^○, and choosing parallel or antiparallel orientation of the monolayer unit cells. The proposed scenarios of the quantum dots and wires formation is based on the multi-scale modelling of electron/hole states on the moiré superlattice considering twirling of domain wall networks upon the reconstruction of the interfaces. We describe crossovers between different positioning of band edges for electrons and holes across moiré superlattices as the twist angle is increased. The spatial variation of the band gap energy gives rise to localization of interlayer excitons as well as contrasting confinement scenarios for intralayer excitons in MX₂ and WX₂, allowing selective population of quantum dot states.