Spectroscopic Signature of Local Alloy Fluctuations in InGaN/GaN Multi-Quantum-Disk Light Emitting Diode Heterostructures and Its Impact on the Optical Performance

TL;DR

This study investigates how local alloy fluctuations in InGaN/GaN multi-quantum-disk LEDs affect their optical performance, revealing that alloy homogeneity improves luminescence properties and carrier localization behavior.

Contribution

It provides new insights into the relationship between alloy composition uniformity and optical performance in InGaN/GaN LEDs.

Findings

Samples with homogeneous alloys show no S-shaped luminescence shift.

Inhomogeneous samples exhibit typical S-shaped temperature dependence.

Optical properties are superior in samples with more uniform alloy composition.

Abstract

Inhomogeneity-governed carrier localization has been investigated in three sets of InGaN/GaN multi-quantum-disk light-emitting diode (LED) structures grown by plasma-assisted molecular beam epitaxy (PAMBE) under different process conditions. A temperature-dependent study of the luminescence peak positions reveals that samples prepared under certain process conditions exhibit a thermal distribution of carriers from the localized states that show the typical S-shaped dependence in luminescence characteristics. The absence of an S-shaped nature in the other sample prepared with relatively higher In-flux infers a superior homogeneity in alloy composition. Further investigation manifested superior optical properties for the samples where the S-shape nature is found to be absent.