We have realized a Dirac fermion reflector in graphene by controlling the ballistic carrier trajectory in a sawtooth-shaped npn junction. When the carrier density in the inner p-region is much larger than that in the outer n-regions, the first straight np interface works as a collimator and the collimated ballistic carriers can be totally reflected at the second zigzag pn interface. We observed clear resistance enhancement around the np+n regime, which is in good agreement with the numerical simulation. The tunable reflectance of ballistic carriers could be an elementary and important step for realizing ultrahigh-mobility graphene field effect transistors utilizing Dirac fermion optics in the near future.
@article{arxiv.1702.04039,
title = {Dirac fermion reflector by ballistic graphene sawtooth-shaped npn junctions},
author = {Sei Morikawa and Quentin Wilmart and Satoru Masubuchi and Kenji Watanabe and Takashi Taniguchi and Bernard Plaçais and Tomoki Machida},
journal= {arXiv preprint arXiv:1702.04039},
year = {2017}
}