Tight-binding calculations of the optical properties of HgTe nanocrystals

Abstract

We propose a tight-binding model of HgTe which gives an accurate band structure in a wide energy range compared to recent ab initio calculations. The inverted band structure near the Fermi level and its temperature dependence are also very well described. Using this parametrization, we study the effects of the quantum confinement on the electronic structure of HgTe quantum dot nanocrystals. We calculate the optical absorption spectra of quantum dots with various shapes and diameters up to 10 nm. We show, using a configuration interaction approach, that excitonic effects are negligible in this range of sizes. Our predictions for the size dependence of the energy gap and for the optical spectra are consistent with recent experimental data.