Lower current density driven InGaN/GaN micro-LED with improved quantum efficiency

In this research article, we propose an engineered electron blocking layer (EBL) structure to address the efficiency degradation in InGaN/GaN multiple quantum well cyan-micro-LEDs grown along a polar orientation at lower current density (1 A/cm²). The engineered EBL structures exhibit improved bandgap continuity that eliminates the creation of an energy pit in the conduction band and a spike in the valence band at the hetero-interface of EBL and the last barrier. Additionally, it targets the quantum-confined Stark effect (QCSE) caused by the electric field induced by polarization through the self-screening of induced polarization charges by grading the Al-composition in the AlGaN EBL along the growth orientation. The strategic EBL engineered structure (Sample B and C) generates polarization-induced bulk charges that effectively compensate for the polarization-induced interface charges and prevent the formation of a robust electric field-related QCSE. Consequently, simulation results for Sample C demonstrate an extraordinary reduction of 1016 times in electron leakage and a substantial improvement in hole injection efficiency compared to the traditional EBL structure (Sample A). The internal quantum efficiency is improved by ∼45%, with a 50% reduction in the required input operating voltage to reach 1 A/cm² compared to Sample A. Finally, efficiency droop at 200 A/cm² is reduced from 45% to 10%, demonstrating enhanced carrier confinement and resolution of electron leakage issues.