Optoelectronics of Inverted Type-I CdS/CdSe Core/Crown Quantum Ring

TL;DR

This study investigates the optoelectronic properties of inverted type-I CdS/CdSe core/crown quantum rings, revealing how their size and composition influence their spectral characteristics and optical gain for potential optoelectronic applications.

Contribution

It provides a comprehensive theoretical analysis of the strain, electronic structure, and optical gain in CdS/CdSe quantum rings considering size, composition, and excitonic effects, using advanced modeling techniques.

Findings

Optical gain is highly dependent on quantum ring dimensions and composition.

Size and composition variations significantly affect energy levels and emission properties.

Maximum and differential optical gains are influenced by carrier injection and quantum ring parameters.

Abstract

Inverted type-I heterostructure core/crown quantum rings (QRs) are quantum-efficient luminophores, whose spectral characteristics are highly tunable. Here, we study the optoelectronic properties of type-I core/crown CdS/CdSe QRs in the zincblende phase - over contrasting lateral size and crown width. For this we inspect their strain profiles, transition energies, transition matrix elements, spatial charge densities, electronic bandstructure, band-mixing probabilities, optical gain spectra, maximum optical gains and differential optical gains. Our framework uses an effective-mass envelope function theory based on the 8-band k$\cdot$p method employing the valence force field model for calculating the atomic strain distributions. The gain calculations are based on the density-matrix equation and take into consideration the excitonic effects with intraband scattering. Variations in the QR lateral size and relative widths of core and crown (ergo the composition) affect their energy levels, band-mixing probabilities, optical transition matrix elements, emission wavelengths/intensity, etc. The optical gain of QRs is also strongly dimension and composition dependent with further dependency on the injection carrier density causing band-filling effect. They also affect the maximum and differential gain at varying dimensions and compositions.