We report on the observation of the reststrahl band assisted photocurrents in epitaxial graphene on SiC excited by infrared radiation. The peculiar spectral dependence for frequencies lying within the reststrahl band of the SiC substrate provides a direct and noninvasive way to probe the electric field magnitude at atomic distances from the material's surface. Furthermore our results reveal that nonlinear optical and optoelectronic phenomena in 2D crystals and other atomic scale structures can be giantly enhanced by a proper combination of the spectral range and substrate material.
@article{arxiv.1308.0123,
title = {Probing of electromagnetic fields on atomic scale by photoelectric phenomena in graphene},
author = {Peter Olbrich and Christoph Drexler and Leonid E. Golub and Sergey N. Danilov and Vadim A. Shalygin and Rositza Yakimova and Samuel Lara-Avila and Sergey Kubatkin and Britta Redlich and Rupert Huber and Sergey D. Ganichev},
journal= {arXiv preprint arXiv:1308.0123},
year = {2013}
}