Optimizing Dirac fermions quasi-confinement by potential smoothness engineering
- 6 February 2020
- journal article
- research article
- Published by IOP Publishing in 2D Materials
- Vol. 7 (2), 025037
- https://doi.org/10.1088/2053-1583/ab734e
Abstract
With the advent of high mobility encapsulated graphene devices, new electronic components ruled by Dirac fermions optics have been envisioned and realized. The main building blocks of electron-optics devices are gate-defined p-n junctions, which guide, transmit and refract graphene charge carriers, just like prisms and lenses in optics. The reflection and transmission are governed by the p-n junction smoothness, a parameter difficult to tune in conventional devices. Here we create p-n junctions in graphene, using the polarized tip of a scanning gate microscope, yielding Fabry-Pérot interference fringes in the device resistance. We control the p-n junctions smoothness using the tip-to-graphene distance, and show increased interference contrast using smoother potential barriers. Extensive tight-binding simulation reveal that smooth potential barriers induce a pronounced quasi-confinement of Dirac fermions below the tip, yielding enhanced interference contrast. On the opposite, sharp barriers are excellent Dirac fermions transmitters and lead to poorly contrasted interferences. Our work emphasizes the importance of junction smoothness for relativistic electron optics devices engineering.Keywords
Funding Information
- Fonds De La Recherche Scientifique - FNRS (CDR project No. J008019F, ERA-Net No. R.50.07.18.F, PDR No. T.1077.15)
- Fédération Wallonie-Bruxelles (16/21-077)
- Deutsche Forschungsgemeinschaft (SPP-1459)
- Horizon 2020 Framework Programme (696656)
- Ministry of Education, Culture, Sports, Science and Technology (JP15K21722, JP25106006, JP26248061)
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