The Effects of Post-Thermal Annealing on the Emission Spectra of GaAs/AlGaAs Quantum Dots grown by Droplet Epitaxy

TL;DR

This study investigates how post-thermal annealing affects the emission spectra of GaAs/AlGaAs quantum dots grown by droplet epitaxy, revealing the relationship between annealing conditions and optical properties.

Contribution

It provides a detailed analysis of emission energy shifts due to annealing and introduces a theoretical model for diffusion length dependence of spectral shifts.

Findings

Emission energy shifts depend on annealing degree

Superlattice peak shifts correlate with dot emission changes

Theoretical diffusion model explains spectral shifts

Abstract

We fabricated GaAs/AlGaAs quantum dots by droplet epitaxy method, and obtained the geometries of the dots from scanning transmission electron microscopy data. Post-thermal annealing is essential for the optical activation of quantum dots grown by droplet epitaxy. We investigated the emission energy shifts of the dots and underlying superlattice by post-thermal annealing with photoluminescence and cathodoluminescence measurements, and specified the emissions from the dots by selectively etching the structure down to a lower layer of quantum dots. We studied the influences of the degree of annealing on the optical properties of the dots from the peak shifts of the superlattice, which has the same composition as the dots, since the superlattice has uniform and well-defined geometry. Theoretical analysis provided the diffusion length dependence of the peak shifts of the emission spectra.