Characterization of Flux-Grown Hexagonal Boron Nitride for Encapsulated 2D Material Devices

For many nanoscale device architectures, van der Waals materials serve as building blocks for device fabrication. One such material, Hexagonal Boron Nitride (hBN), is commonly used in 2D materials research as a transparent gate dielectric and encapsulating layer. We present a growth method for hBN synthesized at the MonArk NSF Quantum Foundry facilities at the University of Arkansas. This talk highlights our characterization of the resulting crystals and their use in encapsulated graphene devices.

Bulk crystals are grown with a Fe-Ni flux at atmospheric pressure. We report Raman spectra matching those shown in the literature for other hBN growth methods. We fabricate parallel-plate capacitor devices using exfoliated thin flakes, obtaining the dielectric constant and breakdown voltage for a range of thicknesses. For comparison, similar devices were fabricated using hBN synthesized by the Taniguchi and Watanabe group at the National Institute for Materials Science of Japan. These results demonstrate that MonArk NSF Quantum Foundry facilities are capable of growing high quality crystals with comparable properties to other commonly used growth methods. We then demonstrate the utility of this hBN crystal growth method by fabricating encapsulated graphene devices and measuring the electronic transport characteristics for each device.