Nicole Urban - Pennsylvania State University
Co-Author(s): Ying Liu and Shaun Mills, Pennsylvania State University, State College, PA
We study two-dimensional (2D) crystals to understand their fundamental physical properties and structural-property relationships. Truly flat 2D crystals cannot be experimentally achieved. Instead, these 2D crystals wrinkle, and sometimes also fold. The wrinkles affect the transport properties of the 2D crystal. For example, curvature in graphene sheets has been shown to be capable of producing a strong pseudo-magnetic field, which can lead to the opening of a Landau level and weak antilocalization. It is therefore important to study the effects of the curvature of a 2D crystal systematically. A novel nanofabrication process developed at Penn State allows the fabrication of electrical transport devices from exfoliated 2D crystals on curved substrates. Our current work includes the preparation of few-layer graphene and NbSe2 by mechanical exfoliation and transferring the exfoliated flakes onto prepatterned metallic contacts, Au with a Ti underlay. Hybrid 2D crystals of NbSe2 and graphene were also prepared. We also tested the contacts between the 2D crystals and AuTi electrodes on a flat substrate. Ohmic contact was made between the NbSe2 and the leads with a contact resistance of less than 530 Ω at 1.8K. Flakes of NbSe2 were found to undergo a superconducting transition at about 6.2K, indicating the quality of the crystal is preserved throughout the process. Work on curved substrate is on going.
Funder Acknowledgement(s): NSF, EFRI
Faculty Advisor: Ying Liu,