Electronic structure of CdTe nanocrystals: A tight-binding study

TL;DR

This study uses a symmetry-based tight-binding approach to analyze the electronic structure of CdTe nanocrystals, revealing that the fundamental interband transition remains dipole-allowed, contrary to previous models.

Contribution

It introduces a symmetry-based tight-binding calculation including spin-orbit interaction for CdTe quantum dots up to 60 Å, providing new insights into their electronic transitions.

Findings

Size-dependent energy gap matches experimental data

Fundamental interband transition remains dipole-allowed

Surface passivation affects electronic states

Abstract

We present a symmetry-based calculation of the electronic structure of a compound semiconductor quantum dot (QD) in the sp^3s* tight-binding model including the spin-orbit interaction. The Hamiltonian matrix is diagonalized exactly for CdTe QD sizes up to 60 {\AA}. The surface dangling bonds are passivated by hydrogen through a careful analysis of the density of states and wave functions. The calculated size dependence of the energy gap shows a reasonable agreement with the available experimental data. Our symmetry analysis indicates that, in contrast with a reported prediction of the three-band effective-mass model, the fundamental interband transition remains dipole-allowed in CdTe nanocrystals.