Creation and Structural Characterization of Moiré-Free Transition Metal Dichalcogenide Heterostructures by Layer Stacking

As a complement to and a method of elucidating the properties of moiré materials formed from stacked 2D transition metal dichalcogenide heterostructures, there is a need for developing epitaxial (i.e., moiré-free) samples. Chemical vapor deposition offers one route to this end. Here, we report the preparation of such samples by means of stacking of well-aligned monolayers and subsequent annealing. We explore this approach for the case of MoSe2/WSe2 heterostructures, which exhibit very slight (~0.6%) intrinsic lattice mismatch. Using torsional force microscopy, we directly visualize the moiré patterns in our initially prepared stacked layers. After a suitable annealing cycle, we find that the initial moiré patterns disappear and are replaced by the micrometer-size epitaxial domains. In this presentation, we will describe the protocol for producing such epitaxial heterostructures and our characterization of their properties, as well as our understanding of the domain boundaries that are created in this process.