Alloy inhomogeneity and carrier localization in AlGaN sections and AlGaN/AlN nanodisks in nanowires with 240-350 nm emission

TL;DR

This study investigates how alloy inhomogeneity and strain relaxation in AlGaN nanostructures affect optical properties, demonstrating tunable emission wavelengths with significant carrier localization despite compositional fluctuations.

Contribution

It provides a detailed analysis of alloy inhomogeneity and strain effects in AlGaN nanostructures, linking these to optical emission characteristics and demonstrating wavelength tunability.

Findings

Alloy inhomogeneity increases with Al content.

Carrier localization signatures are enhanced by alloy fluctuations.

Emission energy can be tuned from 240 to 350 nm with ~30% efficiency.

Abstract

The Al-Ga intermixing at Al(Ga)N/GaN interfaces in nanowires and the chemical inhomogeneity in AlxGa1-xN/AlN nanodisks (NDs) are attributed to the strain relaxation process. This interpretation is supported by the three-dimensional strain distribution calculated by minimizing the elastic energy in the structure. The alloy inhomogeneity increases with Al content, leading to enhanced carrier localization signatures in their optical characteristics i.e. red shift of the emission, s-shaped temperature dependence and linewidth broadening. Despite these alloy fluctuations, the emission energy of AlGaN/AlN NDs can be tuned in the 240-350 nm range with internal quantum efficiencies around 30%.