Engineering surface forces to enable large-area fabrication of two-dimensional material heterostructures

Two-dimensional (2D) materials and their heterostructures have emerged as a leading platform for next-generation devices with unique functionalities. Fabricating such heterostructures from synthetically grown 2D materials can allow higher scalability, however a transfer process is typically needed to place the 2D materials on desired surfaces. This process often involves a sacrificial carrier layer and can introduce contaminants, mechanical defects and degrade the properties of both the 2D material and the substrate. An alternative fabrication technique that allows for clean and large-area integration of 2D materials with diverse material systems is essential. In this talk we show that by engineering surface forces we can achieve such a clean transfer for both graphene and transition metal dichalcogenide monolayers, without the need for a sacrificial layer. Combining this nanoscale surface engineering with aligned transfer printing, we demonstrate large-area, dry transfer of patterned 2D materials with near-unity yield. Utilizing this technique, we further realize structures that are difficult to fabricate using conventional transfers, including 2D materials integrated with atomically flat metal surfaces, molecular layers for deterministic doping, and suspended structures.