laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Seminar, 20st January 2017 (14h00 L363-365)

Sébastien Nanot, L2C, Laboratoire Charles Coulomb – Université de Montpellier - CNRS
Graphene in the mid-infrared : pn junctions for high responsivity photodetectors, acoustic Dirac plasmons with few nanometer confinement

Mid-infrared technology (2-20μm wavelength) could benefit from various graphene properties. In particular, photodetectors based on pn junctions exhibit fast and efficient response in the visible and terahertz ranges, but in the intermediate wavelength range, this response is limited by the graphene small absorption and device design [1,2]. Light absorption can then be strongly enhanced by exciting plasmons in nanostructured graphene[3], but until now, experimental absorption peaks are weaker and broader than they could theoretically be. This presentation will combine some of our recent studies regarding 1) the development and optimization of photodetectors based either on the photothermoelectric effect and (polymer) transparent gates[4], or on the photogating of graphene by pyro-resistive substrates[5,6] ; and 2) a new method to couple light to graphene plasmons by placing a metallic rod array at a nanometer scale distance to the graphene, which efficiently excites acoustic plasmon modes which are vertically confined down to 2 nm [7], while preserving the graphene quality.

[1] M. Badioli, et al., Nano Lett. 14, 6374−6381 (2014).
[2] P.K. Herring, et al., Nano Lett. 14, 901−907 (2014).
[3] M.Freitag, et al., Nat. Comm. 4, 1951 (2013).
[4] C. Peng*, D. K. Efetov*, S. Nanot*, et al. , ArXiv, 1610.07646 (2016).
[5] K.K. Gopalan, et al., ArXiv, 1609.02041 (2016). Accepted in Adv. Opt. Mat.
[6] U. Sassi, et al, ArXiv, 1608.00569 (2016). Accepted in Nat. Comm.
[7] D. Alcaraz Iranzo*, S. Nanot*, et al., submitted.