STM Spectroscopy of ultra-flat graphene on hexagonal boron nitride

STM Spectroscopy of ultra-flat graphene on hexagonal boron nitride

November 26, 2024 | Jiamin Xue, Javier Sanchez-Yamagishi, Danny Bulmash, Philippe Jacquod, Aparna Deshpande, K. Watanabe, T. Taniguchi, Pablo Jarillo-Herrero, and Brian J. LeRoy
This paper investigates the electronic properties of graphene on hexagonal boron nitride (hBN) using scanning tunneling microscopy (STM). The authors demonstrate that graphene conforms to the hBN substrate, as evidenced by the presence of Moiré patterns in STM images. However, contrary to recent predictions, this conformation does not lead to a significant band gap due to the misalignment of the lattices. Local spectroscopy measurements show that electron-hole charge fluctuations are reduced by two orders of magnitude compared to those on silicon oxide, leading to charge fluctuations similar to those in suspended graphene. This reduction in disorder and charge inhomogeneity makes the Dirac point physics more accessible in graphene on hBN devices, opening up new possibilities for diverse experiments. The study also highlights the advantages of using hBN as a substrate over silicon dioxide, which has high roughness and trapped charges, leading to electron and hole doped regions that limit device performance. The results provide insights into the electronic properties of graphene on hBN and suggest that this substrate can offer a substrate-supported system with reduced disorder, making it suitable for studying the low-density regime and Dirac point physics.This paper investigates the electronic properties of graphene on hexagonal boron nitride (hBN) using scanning tunneling microscopy (STM). The authors demonstrate that graphene conforms to the hBN substrate, as evidenced by the presence of Moiré patterns in STM images. However, contrary to recent predictions, this conformation does not lead to a significant band gap due to the misalignment of the lattices. Local spectroscopy measurements show that electron-hole charge fluctuations are reduced by two orders of magnitude compared to those on silicon oxide, leading to charge fluctuations similar to those in suspended graphene. This reduction in disorder and charge inhomogeneity makes the Dirac point physics more accessible in graphene on hBN devices, opening up new possibilities for diverse experiments. The study also highlights the advantages of using hBN as a substrate over silicon dioxide, which has high roughness and trapped charges, leading to electron and hole doped regions that limit device performance. The results provide insights into the electronic properties of graphene on hBN and suggest that this substrate can offer a substrate-supported system with reduced disorder, making it suitable for studying the low-density regime and Dirac point physics.
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[slides and audio] Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride.