Nanostructuring 2D materials and layering them in stacks are key processing steps to building complex 2D material structures and enabling novel applications in photonics and sensing. Whereas growth, patterning and transfer of individual 2D materials has reached industrial-level quality, making useful structures of different materials has been elusive due to the buildup of contaminants during layering and difficulties in aligning the different materials.

Project LEAF-2D, funded by the Horizon 2020 programme of the European Commission, has the task of developing and utilizing laser-assisted transfer of 2D materials for contaminant-free and precise stacking of heterostructures with micrometric precision.

The laser transfer process is chemical-free and does not introduce additional structural defects. It can be used to transfer 2D materials onto any substrate, including flexible or transparent ones. The consortium, led by the National Technical University of Athens, is joined by the University of Southampton, Bar-Ilan University, Mellanox Technologies, Graphenea, and Exelixis. The team has already succeeded in transferring graphene patches as large as tens of micrometers in diameter to a precise target location. The process utilizes high-power femtosecond laser pulses to peel material off the substrate. The material is then attracted by the laser field towards the target substrate.

The final year of the project will be devoted to fabrication of useful devices, such as near-infrared silicon-based emitters and single-layer graphene pixels on flexible substrates for ultra-thin sensors.