The Origin of Stokes Shift in Semiconductor Quantum Dots

TL;DR

This paper investigates the origin of Stokes shift in semiconductor quantum dots by calculating excitonic energies, considering multiple effects, and comparing results with experimental data to identify exchange splitting as the key mechanism.

Contribution

It introduces a comprehensive calculation of excitonic energies including dielectric mismatch, barrier effects, and exchange interaction to explain the Stokes shift in quantum dots.

Findings

Exchange splitting explains the Stokes shift.

Calculated shifts match experimental data.

Size dependence of Stokes shift is demonstrated.

Abstract

The mechanism of Stokes shift in semiconductor quantum dots is investigated by calculating the energy of the excitonic states. We have taken into account all possible contributions to the total electronic energy in the dot, i.e, dielectric mismatch between dot and surrounding medium, the effects of finite barrier height and electron-hole exchange interaction. The Stokes shift is calculated as a function of radius of dot and compared with experimental data on two different semiconductor based quantum dots. These results provide evidence for exchange splitting of excitonic states, as the mechanism of Stokes shift in quantum dot