Green InGaN/GaN LEDs: High luminance and blue shift

TL;DR

This paper investigates the electro-optical behavior of InGaN/GaN green micro-LEDs, revealing a blue shift at high injection levels and suggesting higher-energy states contribute to this shift, challenging traditional models.

Contribution

It presents novel experimental insights into size-dependent electro-optical performance and the blue shift phenomenon in green micro-LEDs, highlighting the role of higher-energy excited states.

Findings

EQE behavior deviates from ABC model predictions

Reduced QCSE at edges of micro-LEDs

Blue shift linked to higher-energy excited states

Abstract

We report in this paper electro-optical results on InGaN/GaN based green micro light-emitting diodes ({\mu}LEDs). Current light-voltage measurements reveal that the external quantum efficiency (EQE) behavior versus charge injection does not follow the ABC model prediction. Light-emission homogeneity investigation, carried out by photoluminescence mapping, shows that the Quantum Confinement Starck Effect (QCSE) is less significant at the edges of {\mu}LEDs. Electroluminescence shows a subsequent color green-to-blue deviation at high carrier injection levels. The extracted spectra at different current injection levels tend to show the appearance of discrete wavelength emissions. These observations may enhance the hypothesis that higher-energy excited-levels in InGaN quantum wells may also contribute to the blue shift, solely attributed to QCSE lessening under intense electric field magnitudes. We hereby present first results dealing with green {\mu}LEDs electro-optical performances with regards to their size.