Fabrication and Characterization of h-BN capped Exfoliated Multi-layer Graphene*

As a 2D material, Graphene has attracted significant interest in recent years. Observation of unconventional superconductivity in twisted bilayer graphene, topological quantum phases, and observation of even denominator FQHE states are some of the exciting new findings [1]. The challenge lies in obtaining large enough single layers of graphene that can be used for device fabrication. Since graphene is sensitive to the surrounding environment, leaving the sample at ambient conditions would heighten the interactions with water and oxygen, increasing impurities and defects. Encapsulating graphene provides significant improvement to the quality of samples. Here we discuss the fabrication and characterization of graphene samples covered from h-BN prepared by mechanical exfoliation and dry transfer method. Optical microscope and AFM imaging were employed in determining the thickness of samples. We studied the transport properties of several µm scale graphene devices with a different number of layers and different geometries. Further, we examine the effect of current annealing on such devices.

[1] Y. Kim et. al., Nature Physics,15 (2019) 154-158.