High resolution imaging of reconstructed domains and moire patterns in functional van der Waals heterostructure devices
arXiv:1912.07446
Abstract
The optical and electronic properties of van der Waals (vdW) heterostructures depend strongly on the atomic stacking order of the constituent layers. This is exemplified by periodic variation of the local atomic registry, known as moire patterns, giving rise to superconductivity and ferromagnetism in twisted bilayer graphene and novel exciton states in transition metal dichalcogenides (TMD) heterobilayers. However, the presence of the nanometer-scale moire superlattices is typically deduced indirectly, because conventional imaging techniques, such as transmission electron microscopy (TEM), require special sample preparation that is incompatible with most optical and transport measurements. Here, we demonstrate a method that uses a secondary electron microscope to directly image the local stacking order in fully hexagonal boron nitride (hBN) encapsulated, gated vdW heterostructure devices on standard Si-substrates. Using this method, we demonstrate imaging of reconstructed moire patterns in stacked TMDs, ABC/ABA stacking order in graphene multilayers, and AB/BA boundaries in bilayer graphene. Furthermore, we show that the technique is non-destructive, thus unlocking the possibility of directly correlating local stacking order with optical and electronic properties, crucial to the development of vdW heterostructure devices with precisely controlled functionality.
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Cited by in corpus (7)
- Charge-polarized interfacial superlattices in marginally twisted hexagonal boron nitride
- Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe/MoSe bilayers
- Guide to optical spectroscopy of layered semiconductors
- Raman imaging of twist angle variations in twisted bilayer graphene at intermediate angles
- Topological phases in N-layer ABC-graphene boron-nitride moire superlattices
- Two dimensional semiconductors: optical and electronic properties
- Phonon Renormalization in Reconstructed MoS Moiré Superlattices