Atomistic tight-binding calculations of near infrared emitting CdxHg1−xTe nanocrystals

Abstract

I present the structural and optical calculations for CdxHg1−xTe zinc-blende nanocrystals with the experimentally synthesized Cd compositions (x) in the framework of atomistic tight-binding model (TB) and configuration interaction description (CI). This atomistic tight-binding model incorporates the sp3s∗ orbital and the first neighbouring interaction, in addition to the non-linear dependence of compositions on the band gaps the bowing factor is involved into this model through the extended virtual crystal approximation (VCA). The information of DOS highlights that the contribution of the conduction and valence bands is subjected by cation and anion atoms, respectively. The improvement of the optical band gaps in CdxHg1−xTe nanocrystals is presented with the increasing Cd compositions. The optical band gaps can be used to tune their optical properties across a technologically useful range from 688nm to 2755nm which can be implemented for the near infrared emitting devices. In addition, the enhancement of the optical property is reported with the increasing Cd contents. With the increasing Cd compositions, the atomistic electron-hole Coulomb interaction is mainly increased, whereas the atomistic electron-hole exchange interaction is reduced. The Stokes shift and fine structure splitting are progressively reduced with the increasing compositions and diameters. The application of fine structure splitting is utilized to implement as a source of entangled photon pairs in the quantum information. Finally, the comprehensive computations of alloy CdxHg1−xTe nanocrystals effectively determine the composition- and size-dependent structural and optical properties which render these nanocrystals promising candidates as the near infrared emitting devices and optical amplifiers.