Resolving the Mystery of Asymmetric Electroluminescence and Photoluminescence in Semiconductor Quantum Wells

Tanveer Ahmed^1*, Der-Hsien Lien¹

¹Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

* Presenter:Tanveer Ahmed, email:tahmed949.ee09@nycu.edu.tw

Electroluminescence (EL) and photoluminescence (PL) characterizations are fundamental instruments to obtain insights on material quality, carrier recombination dynamics, and device efficiencies of light-emitting diodes (LEDs). EL and PL characteristics of LEDs are often observed to differ from each other, though the underlying recombination mechanisms are the same. In this study, the above-mentioned discrepancy is unambiguously resolved using EL and PL characteristics of InGaN-based blue/green and AlGaInP-based red micro-LEDs (μ-LEDs). It is discovered that the photovoltage generated during the optical excitation of LEDs causes an imbalance between the electron and hole populations in the active region leading to an altered PL emission behavior compared to EL. The conventional ABC model is found to be valid for EL only, while an amended ABC model, incorporating the identified phenomenon, is presented to explain the PL emission behavior. The amended ABC model adequately fits the experimental data across different materials and emission wavelengths, establishing the accuracy of the proposed physics.

Keywords: Photoluminescence, Electroluminescence, Light-emitting diodes, Semiconductor quantum wells, Semiconductor/optoelectronic devices