Advantages of Blue LEDs With Graded-Composition AlGaN/GaN Superlattice EBL

Abstract

InGaN/GaN light-emitting diodes (LEDs) with graded-composition AlGaN/GaN superlattice (SL) electron blocking layer (EBL) were designed and grown by metal-organic chemical vapor deposition. The simulation results demonstrated that the LED with a graded-composition AlGaN/GaN SL EBL have superior hole injection efficiency and lower electron leakage over the LED with a conventional AlGaN EBL or normal AlGaN/GaN SL EBL. Therefore, the efficiency droop can be alleviated to be ∼20% from maximum at an injection current of 15-120 mA, which is smaller than that for conventional AlGaN EBL (30%). The corresponding experimental results also confirm that the use of a graded-composition AlGaN/GaN SL EBL can markedly enhance the light output power by 60%.Index Terms-Light-emitting diodes (LEDs), quantum well (QWs), superlattice (SL).

A machine learning study on superlattice electron blocking layer design for AlGaN deep ultraviolet light-emitting diodes using the stacked XGBoost/LightGBM algorithm

“…[21][22][23] Although the graded SL-EBL and AlInGaN-based SL-EBL are proposed in DUV LEDs for optimization, the conventional AlGaN/AlGaN periodic SL-EBL may be preferred due to the lower growth complexity. [24][25] The design of the SL-EBL is usually dependent on the simulation software. The different combinations of composition and thickness are basic variables contributing to the various device capabilities.…”

Deep Ultraviolet AlGaN-Based Light-Emitting Diodes with p-AlGaN/AlGaN Superlattice Hole Injection Structures

“…The p-type AlGaN/GaN heterojunction [18][19][20] and the AlGaN/GaN superlattice (SL) [21][22][23][24][25][26][27][28] have been reported to increase the hole concentrations of p-type GaN-based materials. Since then, similar concepts have been applied in many studies on GaN-based LEDs; such concepts include AlGaN/GaN/AlGaN quantum wells [29,30], AlGaN/GaN SLs [31], and graded AlGaN/GaN SLs [32,33]. Considering that the p-type AlGaN/GaN SL structure has presented promising results in GaN-based LEDs, a similar idea has been adopted to improve the hole concentration of high-Al content AlGaN in DUV LEDs [34,35].…”

Improved Performance of GaN-Based Ultraviolet LEDs With Electron Blocking Layers Composed of Double-Peak p-Type Al x Ga1−x N/GaN Superlattice Layers

“…Zhang and Yin [17] investigated two types of AlGaN/GaN SL-EBL structures in GaN-based LEDs, and found that the SL-EBL with a step-graded Al molar fraction markedly decreased the efficiency droop. Lin et al [18] reported that the application of an AlGaN/GaN SL-EBL in GaN-based LEDs markedly enhanced the optical power output by as much as 60%. While the above-discussed studies have demonstrated the optimal Al-grading structure of these SL-EBLs, the mechanism remains unclear owing to a lack of systematic investigation.…”