The Strong Confinement Regime in HgTe Two-Dimensional Nanoplatelets

The confinement in colloidal HgTe nanocrystals enables this material to be promising for colloidal optoelectronics over a wide range of energies, from the THz spectral range up to the visible region. Herein, using a combination of high-energy-absorption HgTe nanoplatelets and low-energy-absorption HgTe nanocrystals, we probe the optical transmission of HgTe nanoparticles over the 0.26-1.8 eV range, from 0 to 300 K temperatures and under simultaneous pressure, up to 4 GPa. While the pressure dependence of nanoplatelets follows the one observed for bulk and nanocrystals, the temperature dependence dramatically differs for nanoplatelets. The modeling of the electronic energy dispersion using up to 14-band k.p formalism suggests that the second conduction band and higher bands of HgTe play a vital role in describing and explaining the HgTe nanoparticle spectroscopies.