Precision Local Strain Engineering in 2D Semiconductors and Their van der Waals Heterostructures.

Two-dimensional (2D) semiconductors and their van der Waals (vdW) heterostructures are readily tuned by strain, an approach known as straintronics, owing to their atomically thin, vdW-bonded layered structures. Small external or environmental perturbations induce strain in adjacent 2D semiconductors, yet sustaining large elastic deformations without fracture. This makes strain a uniquely powerful lever for reconfiguring lattice structure and deterministically tuning band structure, carrier transport, and excitonic responses. In this review, we survey experimental methodologies for quantifying and mapping local strain in 2D semiconductors, and summarize state-of-the-art strategies for imparting strain, including substrate-mediated deformation, patterned stressors, and interlayer-interaction-driven strain in stacked vdW heterostructures. Building on these foundations, we discuss how advances in precise local strain control are informing new device concepts and outline pathways for integrating strain programmability into scalable architectures. We conclude by identifying key challenges and opportunities toward robust, wafer-compatible deployment of local strain engineering in 2D semiconductor technologies.