Proximity screening greatly enhances electronic quality of graphene
Daniil Domaretskiy, Zefei Wu, Van Huy Nguyen, Ned Hayward, Ian Babich, Xiao Li, Ekaterina Nguyen, Julien Barrier, Kornelia Indykiewicz, Wendong Wang, Roman Gorbachev, Na Xin, Kenji Watanabe, Takashi Taniguchi, Lee Hague, Vladimir I. Fal’ko, I. V. Grigorieva, Л. А. Пономаренко, Alexey I. Berdyugin, A. K. Geǐm
Abstract
Abstract The electronic quality of two-dimensional systems is crucial when exploring quantum transport phenomena. In semiconductor heterostructures, decades of optimization have yielded record-quality two-dimensional gases with transport and quantum mobilities reaching close to 10 8 and 10 6 cm 2 V −1 s −1 , respectively 1–10 . Although the quality of graphene devices has also been improving, it remains comparatively lower 11–17 . Here we report a transformative improvement in the electronic quality of graphene by employing graphite gates placed in its immediate proximity, at 1 nm separation. The resulting screening reduces charge inhomogeneity by two orders of magnitude, bringing it down to a few 10 7 cm −2 and limiting potential fluctuations to less than 1 meV. Quantum mobilities reach 10 7 cm 2 V −1 s −1 , surpassing those in the highest-quality semiconductor heterostructures by an order of magnitude, and the transport mobilities match their record 9,10 . This quality enables Shubnikov–de Haas oscillations in fields as low as 1 mT and quantum Hall plateaux below 5 mT. Although proximity screening predictably suppresses electron–electron interactions, fractional quantum Hall states remain observable with their energy gaps reduced only by a factor of 3–5 compared with unscreened devices, demonstrating that many-body phenomena at spatial scales shorter than 10 nm remain robust. Our results offer a reliable route to improving electronic quality in graphene and other two-dimensional systems, which should facilitate the exploration of new physics previously obscured by disorder.