Analysis of optical properties of strained semiconductor quantum dots for electromagnetically induced transparency

TL;DR

This study investigates how size, shape, strain, and band mixing influence the optical properties and EIT efficiency in semiconductor quantum dots, identifying optimal conditions and effects of complex band interactions.

Contribution

It introduces a comprehensive analysis of strain and band mixing effects on EIT in quantum dots using multiband k*p theory, highlighting optimal geometries and transition behaviors.

Findings

V-type scheme is most favorable for EIT in quantum dots.

Strain and band mixing significantly affect transition strengths and energy levels.

Optimal quantum dot dimensions enhance EIT performance.

Abstract

Using multiband k*p theory we study the size and geometry dependence on the slow light properties of conical semiconductor quantum dots. We find the V-type scheme for electromagnetically induced transparency (EIT) to be most favorable, and identify an optimal height and size for efficient EIT operation. In case of the ladder scheme, the existence of additional dipole allowed intraband transitions along with an almost equidistant energy level spacing adds additional decay pathways, which significantly impairs the EIT effect. We further study the influence of strain and band mixing comparing four different k*p band structure models. In addition to the separation of the heavy and light holes due to the biaxial strain component, we observe a general reduction in the transition strengths due to energy crossings in the valence bands caused by strain and band mixing effects. We furthermore find a non-trivial quantum dot size dependence of the dipole moments directly related to the biaxial strain component. Due to the separation of the heavy and light holes the optical transition strengths between the lower conduction and upper most valence-band states computed using one-band model and eight-band model show general qualitative agreement, with exceptions relevant for EIT operation.