Enhanced Efficiency of Deep Ultraviolet μLEDs Through Graded-Last Quantum Barrier Integration

The optoelectronic properties of 25 um Aluminum Gallium Nitride (AlGaN) deep ultraviolet micro light emitting diodes (μLEDs) is enhanced by the graded last quantum barrier (G-LQB). The simulation is carried out through SiLENSe™ software, which considers the internal quantum efficiency (IQE), recombination rates, energy bands of heterostructure, carrier transport, and carrier distribution in active regions. The improved structure exhibits a higher internal quantum efficiency (IQE) and a reduced efficiency droop of 5%, compared to 8% in the conventional design. This enhancement is attributed to an increase in the conduction band barrier height for electrons at the G-LQB position, which prevents electrons from entering the p-region. Additionally, the stronger electric field at the interface between the G-LQB and the electron blocking layer (EBL) creates an energy dip that captures some of the electrons, reducing leakage and resulting in a higher electron concentration in the active region compared to conventional designs. Furthermore, the injection of holes is improved due to a reduction in the valence band barrier height. The radiative recombination rates increase by 25%, and the emission intensity becomes double as compared to the conventional structure. The enhanced optical and electrical performance of AlGaN-based μLEDs is due to high carrier transport in the active region at low current density, which results in high radiative recombination of electrons and holes and thus high IQE. Therefore, this study is crucial for the design of high-performance AlGaN-based deep ultraviolet μLEDs.