American Chemical Society
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Vanishing Confinement Regime in Terahertz HgTe Nanocrystals Studied under Extreme Conditions of Temperature and Pressure

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journal contribution
posted on 2022-07-22, 17:41 authored by Stefano Pierini, Francesco Capitani, Michael Scimeca, Sergei Kozlov, Debora Pierucci, Rodolphe Alchaar, Claire Abadie, Adrien Khalili, Mariarosa Cavallo, Tung Huu Dang, Huichen Zhang, Erwan Bossavit, Charlie Gréboval, José Avila, Benoit Baptiste, Stefan Klotz, Ayaskanta Sahu, Cheryl Feuillet-Palma, Xiang Zhen Xu, Abdelkarim Ouerghi, Sandrine Ithurria, James K. Utterback, Sebastien Sauvage, Emmanuel Lhuillier
While HgTe nanocrystals (NCs) in the mid-infrared region have reached a high level of maturity, their far-infrared counterparts remain far less studied, raising the need for an in-depth investigation of the material before efficient device integration can be considered. Here, we explore the effect of temperature and pressure on the structural, spectroscopic, and transport properties of HgTe NCs displaying an intraband absorption at 10 THz. The temperature leads to a very weak modulation of the spectrum as opposed to what was observed for strongly confined HgTe NCs. HgTe NC films present ambipolar conduction with a clear prevalence of electron conduction as confirmed by transistor and thermoelectric measurements. Under the application of pressure, the material undergoes phase transitions from the zinc blende to cinnabar phase and later to the rock salt phase which we reveal using joint X-ray diffraction and infrared spectroscopy measurements. We discuss how the pressure existence domain of each phase is affected by the particle size.