Engineering electronic materials with atomic precision will enable construction of tailored quantum devices exhibiting unique electronic, magnetic and optical properties, with the potential to impact fields ranging from quantum information science to next-generation computing and clean energy technologies. Atomically precise vertical structures can be formed by stacking different atomically-thin materials with diverse characteristics. The properties of individual layers, and their emergent interactions, show great promise for fundamental science and future technologies. To date, this process has been explored at the artisanal scale and has generated a wealth of scientific discoveries. However, the scalable construction of such heterostructures has remained a challenge, with individual stacks often built up though painstakingly manual processes with significant interfacial contamination. This project overcomes these challenges and enables scalable production of atomically-resolved heterostructures by developing an automated robotic platform to assemble layer materials under ultra-high vacuum conditions, resulting in a tool for production of materials with unprecedented complexity and interfacial cleanliness. Once developed, this system will be housed adjacent to the Stanford Nanofabrication Facility, where it will serve as a shared tool for Stanford researchers across a diverse interdisciplinary community. Additionally, this project will enhance undergraduate and graduate education through advanced coursework and research opportunities.
This project supports development of a novel instrument to automate the fabrication of designer quantum materials in the form of layered van der Waals (vdW) heterostructures. Existing processes which exclusively utilize exfoliated materials are limited by the stochastic nature of the samples, resulting in low throughput and geometric constraints on the resulting heterostructure. In contrast, this project utilizes both exfoliated and chemical vapor deposition (CVD)/molecular beam epitaxy (MBE)-grown source materials for enhanced throughput and improved sample size. The instrument employs interconnected ultra-high vacuum (UHV) chambers to maintain atomically pristine surfaces, and uses precision nanopositioning stages, microstructured adhesive effectors, an optical microscope, and computer vision algorithms to enable user-friendly, high-throughput fabrication and deposition onto arbitrary substrates. The UHV sample preparation chamber and vacuum suitcase facilitate inert sample processing, enabling study of air-sensitive 2D materials. Integrated in-situ UHV-CVD growth of large area, single-crystal graphene and hBN provide access to pristine samples which are critical to the investigation of vdW heterostructures with controlled rotational alignment. This instrument enables the study of diverse topics in condensed matter physics and materials science, including engineered strongly correlated phases in twisted many-layer structures, emergent topological superconductivity at heterointerfaces, and precisely localized studies of single-defect quantum devices. The five-year development project for this instrument enables a diverse team of Stanford researchers to explore these phenomena, and provides a nucleation point for collaboration across academia and industry.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
