Van Der Waals Heterostructures

The integration of dissimilar materials into heterostructures has become a powerful tool for engineering interfaces and electronic structure. The advent of 2D materials has provided unprecedented opportunities for novel heterostructures in the form of van der Waals stacks, laterally stitched 2D layers and more complex layered and 3D architectures. This Primer provides an overview of state-of-the-art methodologies for producing such van der Waals heterostructures, focusing on the two fundamentally different strategies, top-down deterministic assembly and bottom-up synthesis. Successful techniques, advantages and limitations are discussed for both approaches. As important as the fabrication itself is the characterization of the resulting engineered materials, for which a range of analysis techniques covering structure, composition and emerging functionality are highlighted. Examples of the properties of artificial van der Waals structures include optoelectronics and plasmonics, twistronics and unique functionality arising from the generalization of van der Waals assembly from 2D to 3D crystalline components. Finally, current issues of reproducibility, limitations and opportunities for future breakthroughs in terms of enhanced homogeneity, interfacial purity, feature control and ultimately orders-of-magnitude increased complexity of van der Waals heterostructures are discussed. Van der Waals epitaxy provides numerous opportunities for materials integration in heterostructures. This Primer provides an overview of methodologies for producing van der Waals heterostructures, focusing on top-down assembly and bottom-up synthesis, and discusses future opportunities for their continued development.