Identify a substrate balancing flexibility and rigidity for strain-tunable vdW devices

Identify a substrate architecture for van der Waals heterostructure devices that is simultaneously flexible enough to enable application of high uniaxial strain and rigid enough to remain compatible with fabrication of state-of-the-art devices on silicon/silicon dioxide wafer substrates.

Background

Van der Waals heterostructure devices are typically fabricated on thick Si/SiO2 wafer substrates, but silicon’s high Young’s modulus makes it difficult to apply large strains using piezoelectric-driven strain cells. The force required to reach ~1% strain in millimeter-scale silicon substrates exceeds typical piezo stack capabilities, motivating the search for alternative approaches.

Prior strategies used flexible substrates (e.g., metals or polymers) in bending geometries or suspended architectures, but these can introduce vertical strain gradients and complicate fabrication of complex dual-gated devices. The paper motivates the need for a substrate solution that preserves compatibility with advanced vdW device fabrication while allowing high levels of tunable uniaxial strain.