2, Université Pierre et Marie Curie, Paris, , France
3, Synctrotron SOLEIL, Saint-Aubin, , France
Among colloidal nanomaterials, 2D nanoplatelets1,2 (NPLs) show remarquable optical properties due to their atomic flatness in the only confined dimension. Those objects are typically strongly confined and thus usually address the visible range. Recently, the synthesis of mercury telluride nanoplatelets with optical features in the near infrared has been reported.3
We have investigated the electronic transport of thin films made of HgTe NPL in an electrolytic filed effect transistor configuration4. We have demonstrated that the majority carrier can be tuned from p-type to n-type using ethanedithiol (EDT) or sulfide (S2-) capping, respectively5. This change of behavior was confirmed by looking at the electronic structure of the material using X-ray photoemission and attributed to a change of hybridization of the ligands with the Hg rich surface of NPL.
We then probed the photophysics of HgTe NPL films, focusing on carriers' dynamics. Using pulsed near-infrared illumination, we measured a response time around 100 µs at the device scale, and wonder whether this value is a material limitation. The answer has been found using time-resolved photoemission where relaxation occurs on a time scale of 100 ns, suggesting that current device performances are limited by geometrical factors rather than physical processes.
1. M. Nasilowski, B. Mahler, E. Lhuillier, S. Ithurria, and B. Dubertret, Chem. Rev. 116, 10934 (2016).
2. E. Lhuillier, S. Pedetti, S. Ithurria, B. Nadal, H. Heuclin, and B. Dubertret, Acc. Chem. Res. 48, 22 (2015).
3. E. Izquierdo, et al., J. Am. Chem. Soc. 138, 10496 (2016).
4. E. Lhuillier, S. Pedetti, S. Ithurria, H. Heuclin, B. Nadal, A. Robin, G. Patriarche, N. Lequeux, and B. Dubertret, ACS Nano 8, 3813 (2014).
5. C. Livache, E. Izquierdo, B. Martinez, M. Dufour, D. Pierucci, S. Keuleyan, H. Cruguel, L. Becerra, J.L. Fave, H. Aubin, A. Ouerghi, E. Lacaze, M.G. Silly, B. Dubertret, S. Ithurria, and E. Lhuillier, Nano Lett. 17, 4067 (2017)