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arXiv · 1305.3297

Sensitive Room-Temperature Terahertz Detection via Photothermoelectric Effect in Graphene

Xinghan Cai·Andrei B. Sushkov·Ryan J. Suess·Mohammad M. Jadidi·Greg S. Jenkins·Luke O. Nyakiti·Rachael L. Myers-Ward·Shanshan Li·Jun Yan·D. Kurt Gaskill·Thomas E. Murphy·H. Dennis Drew·Michael S. Fuhrer
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Abstract

Terahertz (THz) radiation has uses from security to medicine; however, sensitive room-temperature detection of THz is notoriously difficult. The hot-electron photothermoelectric effect in graphene is a promising detection mechanism: photoexcited carriers rapidly thermalize due to strong electron-electron interactions, but lose energy to the lattice more slowly. The electron temperature gradient drives electron diffusion, and asymmetry due to local gating or dissimilar contact metals produces a net current via the thermoelectric effect. Here we demonstrate a graphene thermoelectric THz photodetector with sensitivity exceeding 10 V/W (700 V/W) at room temperature and noise equivalent power less than 1100 pW/Hz^1/2 (20 pW/Hz^1/2), referenced to the incident (absorbed) power. This implies a performance which is competitive with the best room-temperature THz detectors for an optimally coupled device, while time-resolved measurements indicate that our graphene detector is eight to nine orders of magnitude faster than those. A simple model of the response, including contact asymmetries (resistance, work function and Fermi-energy pinning) reproduces the qualitative features of the data, and indicates that orders-of-magnitude sensitivity improvements are possible.

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Xinghan Cai, Andrei B. Sushkov, Ryan J. Suess, Mohammad M. Jadidi, Greg S. Jenkins, Luke O. Nyakiti, Rachael L. Myers-Ward, Shanshan Li, Jun Yan, D. Kurt Gaskill, Thomas E. Murphy, H. Dennis Drew, Michael S. Fuhrer. 2014-09-13. Sensitive Room-Temperature Terahertz Detection via Photothermoelectric Effect in Graphene. https://doi.org/10.1038/nnano.2014.182

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