Via Method for Lithography Free Contact and Preservation of 2D Materials

Atomically thin 2D materials span the common electronic material properties such as metals, semi-conductors, and insulators, and can manifest correlated phases such as superconductivity, charge density waves, and magnetism. An ongoing challenge in the field is to incorporate these 2D materials into multi-layer hetero-structures with robust electrical contacts while preventing disorder and degradation. In particular, preserving and studying air-sensitive 2D materials has presented a significant challenge since they readily oxidize under atmospheric conditions. We report a new technique for contacting 2D materials, in which metal ‘via’ contacts are pre-patterned into insulating h-BN layers, which are then placed onto the desired conducting 2D layer, avoiding direct lithographic patterning onto the 2D conductor. The metal contacts are planar with the bottom surface of the h-BN and form robust contacts to multiple 2D materials, as well as 1D carbon nanotubes. These structures protect air-sensitive 2D materials for months with no degradation in performance while providing electrical contact exceeding the best techniques previously demonstrated. This technique will provide the capability to produce ‘atomic PCBs’ that can form the basis of more complex multi-layer heterostructures.