Correlation between In content and emission wavelength of InGaN/GaN nanowire heterostructures

TL;DR

This study investigates how varying indium content in InGaN/GaN nanowire heterostructures affects their emission wavelength and luminescence properties, revealing complex localization effects and a correlation between composition and emission energy.

Contribution

It provides detailed analysis of the relationship between In content and emission wavelength in nanowire heterostructures, including statistical composition data and modeling of carrier localization effects.

Findings

In content ranges from nearly 0% to 20%.

Photoluminescence shifts from 2.2 eV to 2.5 eV with In content.

Luminescence intensity increases with In content, contrary to planar structures.

Abstract

GaN nanowire ensembles with axial InGaN multi-quantum wells (MQWs) were grown by molecular beam epitaxy. In a series of samples, we varied the In content in the MQWs from almost zero to about 20%. Within the nanowire ensemble, the MQWs fluctuate strongly in composition and size. Statistical information about the composition was obtained from x-ray diffraction and Raman spectroscopy. Photoluminescence at room temperature was obtained in the range from 2.2 eV to 2.5 eV depending on In content. Contrary to planar MQWs, the intensity increases with increasing In content. We compare the observed emission energies with transition energies obtained from a one-dimensional model, and conclude that several mechanisms for carrier localization affect the luminescence of these three-dimensional structures.