Why does it matter? Van der Waals heterostructures are built by stacking atomically thin crystals without the constraints of lattice matching that limit conventional semiconductor fabrication.

This freedom allows researchers to combine materials with very different electronic and structural properties, such as conductive graphene and insulating hBN, into a single engineered stack. The quality of these stacks depends heavily on how the layers are assembled. Standard transfer methods rely on polymer stamps, which pick up and release flakes through controlled heating, but often leave behind polymeric residue that can degrade the interface and limit the precision of certain measurements.

By replacing the polymer film with a mica membrane, a van der Waals crystal in its own right, this work aims to reduce contamination and produce smoother, cleaner heterostructures, even though mica's rigidity introduces new challenges in achieving reliable, uniform contact during the transfer process.