Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Domaines cond-mat
Date Lundi 3 Fevrier 2020
Heure 13:30
Institut LPENS
Salle Conf IV
Nom de l'orateur Lhuillier
Prenom de l'orateur Emmanuel
Addresse email de l'orateur
Institution de l'orateur Institut des NanoSciences de Paris
Titre Narrow band gap nanocrystals as building block for infrared sensors
Résumé While the integration of nanocrystals for display application has demonstrated the viability of these nanomaterials for a mass market, their use for infrared sensing appears also quite promising. When infrared wavelengthes are considered, I will show that HgTe nanocrystals offer a unique combination of broadly tunable optical absorption in the infrared from 1 to 100 µm [1 and top part of figure] and photoconductive properties. However, the maturity of the current device remains far weaker what have been achieve for solar cell using PbS nanocrystals. Current limitations are the result of limited material development and poor understanding of the electronic structure of the material under colloidal form. In this talk, I will discuss some of the recent developments relative to HgTe nanocrystal integration into photodiodes operating in the short wave and mid wave infrared. I will present how the concepts of unipolar barrier has been transferred from III-V semiconductor to colloidal HgTe nanocrystal film [2]. Another important limitation to address is tradeoff between the absorption depth (> 1 µm) and the carrier diffusion length (< 100 nm) which make that most current devices have a weak light absorption (10 % of the incident light typically). This issue can be addressed by two strategies which are the development of ink to achieve thick high mobility film [3] and by enhancing the light matter coupling thanks to the introduction of plasmonic resonator (bottom left part of figure). I will briefly also report about recent development relative to the integration into focal plane array to conduct imaging (bottom right part of figure). Finally, I will discuss about how it is possible to take advantage of intraband transitions in self doped nanocrystal to design mid wave infrared detector [4-5]. I will in particular discuss how early limitations of the doped nanocrystals (large dark current in particular) can be overcome by carefully engineering the energy landscape of the nanocrystal film. To reach this goal design inspired from II-V semiconductor has been used. References [1] Terahertz HgTe nanocrystals: beyond confinement, N. Goubet, A. Jagtap, C. Livache, B. Martinez, H. Portales, X. Zhen Xu, R.P.S.M. Lobo, B. Dubertret, E. Lhuillier, J. Am. Chem. Soc. 140, 5053 (2018). [2] Design of Unipolar Barrier for Nanocrystal Based Short Wave Infrared Photodiode, A.Jagtap, B. Martinez, N. Goubet, A. Chu, C. Livache, C. Greboval, J. Ramade, D. Amelot, P. trousset, A. triboulin, S. Ithurria, M. G. Silly, B. Dubertret, E. Lhuillier, ACS Phot. 5, 4569 (2018) [3] HgTe Nanocrystal Inks for Extended Short Wave Infrared Detection, B. Martinez, J. Ramade, C. Livache, N. Goubet, A. Chu, C. Gréboval, J. Qu, W. L. Watkins L. Becerra, E. Dandeu, J.-L. Fave, C. Méthivier, E. Lacaze, E. Lhuillier, Adv Opt Mat 1900348 (2019). [4] Infrared photo-detection based on colloidal quantum-dot films with high mobility and optical absorption up to the THz, E. Lhuillier, M. Scarafagio, P. Hease, B. Nadal, H. Aubin, X. Z. Xu, N. Lequeux, G. Patriache, S. Ithurria, B. Dubertret, Nano Lett 16, 1282 (2016) [5] A Colloidal Quantum Dot Infrared Photodetector and its use for Intraband Detection, C. Livache, B. Martinez, N. Goubet, C. Greboval, J. Qu, A. Chu, S. Royer, S. Ithurria, M. G. Silly, B. Dubertret, E. Lhuillier, Nature Comm 10, 2125 (2019)
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