HgX nanocrystals as building block for IR sensing

Datum: 17 januari 2020

Locatie: UAntwerp, Campus Groenenborger, Room U.408 - Groenenborgerlaan 171 - 2020 Antwerpen - Wilrijk (route: UAntwerpen, Campus Groenenborger)

Tijdstip: 11.30 - 12.30 uur

Organisatie / co-organisatie: EMAT

Korte beschrijving: Friday Lecture by Emmanuel Lhuillier, Nanoscience Institute of Paris



About the lecture

HgTe nanocrystals offer a unique combination of broadly tunable optical absorption in the infrared from 1 to 100 µm 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 [1].

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 [2] and by enhancing the light matter coupling thanks to the introduction of plasmonic resonator. I will briefly also report about recent development relative to the integration into focal plane array to conduct imaging.

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 [3]. 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. 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)
  2. 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)
  3. 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)


Link: https://www.uantwerpen.be/en/research-groups/emat/news-and-activities/friday-lectures/