Theoretical Analysis of the Strong Confinement in HgTe Nanostructures Using a 14-band k.p Formalism

Sébastien Sauvage^a, Guy Fishman^b, Nicolas Moghaddam^c, Charlie Gréboval^d, Junling Qu^d, Audrey Chu^d, Prachi Rastogi^d, Clément Livache^d, Adrien Khalili^c, Xiang Zhen Xu^c, Benoit Baptiste^e, Stefan Klotz^e, Francesco Capitani^f, Sandrine Ithurria^c, Emmanuel Lhuillier^d

^aC2N, Centre de Nanosciences et de Nanotechnologies, CNRS, University Paris-Saclay

^bKadope, C2N

^cLPEM, Laboratoire de Physique et d’Etude des Matériaux, ESPCI-ParisTech, PSL Research University, Sorbonne Université UPMC Univ Paris 06, CNRS

^dINSP, Institut des Nanosciences de Paris, Sorbonne Université, CNRS

^eIMPMC, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, CNRS

^fSynchrotron-SOLEIL, BP 48, Saint-Aubin, F91192, Gif-sur-Yvette Cedex, France, France

Materials for Sustainable Development Conference (MATSUS)
Proceedings of Online nanoGe Fall Meeting 20 (OnlineNFM20)

#INfraNC20. Infrared Nanocrystals

Online, Spain, 2020 October 20th - 23rd

Organizers: Emmanuel Lhuillier and Philippe Guyot-Sionnest

Poster, Sébastien Sauvage, 246
Publication date: 4th October 2020

ePoster:

HgTe nanoplatelets, only 3 monolayers 1.1 nm thick, exhibit extreme confinement. Despite HgTe being a vanishing band gap semiconductor, with natural optical properties in the infrared spectral range, absorption energies of HgTe nanoplatelets are observed to be as high as 1.5 eV.[1] These energies correspond to state wave vectors far away from the zone center, around 15% of the Brillouin zone edge. Contrarily to atomistic modeling, the commonly used effective mass, 2-bands or even 8-bands k.p formalisms fail to describe the non-parabolicity of the dispersion relation E(k) around these relatively high energies. We have developed a single strain-dependent 14-bands k.p framework to extract the electronic structure of HgTe nanoplatelets and nanocrystals in a large range of energies (0.26-1.8 eV), temperatures (0-300 K) and pressures (up to 4 GPa).[1] Despite setting aside Coulomb electron-hole and electron-phonon interaction corrections, the 14-band model reasonably accounts for the observed surprising temperature and pressure absorption spectroscopy. The modeling of the electronic energy dispersion suggests that the second set of conduction bands of HgTe play a key role to describe and explain the observed HgTe nanoplatelets and small HgTe nanocrystals absorption.

References:

[1] Moghaddam, N.; Gréboval, C.; Qu, J.; Chu, A.; Rastogi, P.; Livache, C.; Khalili, A.; Xu, X. Z.; Baptiste, B.; Klotz, S.; Fishman, G.; Capitani, F., Ithurria, S., Sauvage, S.; Lhuillier, E; J. Phys. Chem. C 2020, in press

Acknowledgements:

We thank Mayank Goyal for participation to synchrotron experiments. This work has been supported by the Region Ile-de-France in the framework of DIM Nano-K (grant dopQD). This work was supported by French state funds managed by the ANR within the Investissements d'Avenir programme by Labex Matisse (ANR-11-IDEX-0004-02), and Labex NanoSaclay (ANR-10-LABX-0035), and also by the grant FRONTAL (ANR-19-CE09-0017), IPER-Nano2 (ANR-18CE30-0023-01), Copin (ANR-19-CE24-0022), Graskop (ANR-19-CE09-0026). JQ thanks Chinese Scholar council for PhD grant while AC thanks Agence Innovation Defense. EL thanks the support ERC starting grant blackQD (grant n° 756225). SI thanks the support ERC starting grant Ne2Dem (grant n° 853049).

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