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Nat Nanotechnol. 2014 Oct;9(10):814-9. doi: 10.1038/nnano.2014.182. Epub 2014 Sep 7.

Sensitive room-temperature terahertz detection via the photothermoelectric effect in graphene.

Author information

1
Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742-4111, USA.
2
Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, USA.
3
Texas A&M University, Galveston, Texas 77553, USA.
4
US Naval Research Laboratory, Washington DC 20375, USA.
5
1] Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742-4111, USA [2] Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA.
6
1] Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742-4111, USA [2] School of Physics, Monash University, 3800 Victoria, Australia.

Abstract

Terahertz radiation has uses in applications ranging from security to medicine. However, sensitive room-temperature detection of terahertz radiation 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 terahertz photodetector with sensitivity exceeding 10 V W(-1) (700 V W(-1)) at room temperature and noise-equivalent power less than 1,100 pW Hz(-1/2) (20 pW Hz(-1/2)), referenced to the incident (absorbed) power. This implies a performance that is competitive with the best room-temperature terahertz detectors for an optimally coupled device, and 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.

PMID:
25194945
DOI:
10.1038/nnano.2014.182

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