Direct-Write Printed Contacts to Layered Materials

The common techniques to create direct contacts to layered materials rely direct-write lithography which requires polymeric resists that leave behind residues that can be impossible to clean. The approach taken in these methods is to eliminate polymers from coming in direct contact with the active channel material and reduce defects induced by the deposition of metal films. However, these methods require many additional steps of fabrication involving dry stamping for encapsulation and several steps of lithography to etch undesired areas, deposit metal contacts, and lift-off. We show that direct-write printing is capable of creating microscale metallic contacts in a single step. We demonstrate that printed contacts are an alternate method to achieve high-quality electrical contacts to different layered materials including graphene, MoS₂, Bi-2212, and Fe₅GeTe₂. We benchmark the printed devices using appropriate measurements, such as gating, resistance vs. temperature, or Hall transport. Our results show that direct-write printing is reliable method to fabricate devices on 2D materials for rapid testing. Printing 2D material devices on flexible and non-uniform substrates can be used for sensors.