We investigate hot carrier propagation across graphene using an electrical nonlocal injection/detection method. The device consists of a monolayer graphene flake contacted by multiple metal leads. Using two remote leads for electrical heating, we generate a carrier temperature gradient that results in a measurable thermoelectric voltage VNL across the remaining (detector) leads. Due to the nonlocal character of the measurement, VNL is exclusively due to the Seebeck effect. Remarkably, a departure from the ordinary relationship between Joule power P and VNL, VNL ~ P, becomes readily apparent at low temperatures, representing a fingerprint of hot-carrier dominated thermoelectricity. By studying VNL as a function of bias, we directly determine the carrier temperature and the characteristic cooling length for hot-carrier propagation, which are key parameters for a variety of new applications that rely on hot-carrier transport.
@article{arxiv.1506.04575,
title = {Hot-Carrier Seebeck Effect: Diffusion and Remote Detection of Hot Carriers in Graphene},
author = {J. F. Sierra and I. Neumann and M. V. Costache and S. O. Valenzuela},
journal= {arXiv preprint arXiv:1506.04575},
year = {2015}
}