Efficient Carrier Confinement in AlGaN‐Based Deep‐Ultraviolet Light‐Emitting Diodes with a Composition‐Graded Electron‐Blocking Layer

Abstract

The serious electron leakage and poor transport of hole injection layers in deep‐ultraviolet (DUV) light‐emitting diodes (LEDs) lead to an imbalance between the hole and electron currents, which reduces the device's performance. Herein, a new DUV LED structure is designed. The aluminum composition of the p‐type electron‐blocking layer (p‐EBL) gradually decreases from 0.95 to 0.75 along the growth direction, replacing the traditional bulk p‐EBL. When the injection current is 100 mA, the optical power of this structure is about 32% higher than that of the traditional structure. In addition, when the p‐EBL adopts the opposite gradient (the Al composition gradually increases from 0.75 to 0.95), the device performance suddenly drops dramatically. The related devices are simulated by Silvaco TCAD software. The results show that the performance outputs of the two opposite aluminum gradient growth modes are completely opposite. The proposed p‐EBL with a gradual step‐down Al composition along the growth direction helps to improve the efficiency of hole injection into multiple quantum wells (MQWs) and reduce the level of electron leakage. This work provides an effective solution for increasing the light output power of high‐performance DUV LEDs.

A Review of Recent Research Advances on AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

“…The step-fading p-AlGaN EBLs are similar to the linear-fading p-AlGaN EBLs in that they also have the effect of improving hole injection and suppressing electron leakage. Ye et al [73] step-fading decreased the Al component of p-AlGaN EBLs along the growth direction as shown in Figure 19. The optical power of AlGaN-based DUV-LEDs was increased by about 32% at 100 mA current.…”

High-Power and High-Efficiency 221 nm AlGaN Far Ultraviolet Laser Diodes

“…6,7 The design and manufacture of devices requiring lower wavelengths of operation for UV sources need Al-rich AlGaN layers. 8,9 Unfortunately, achieving highly crystalline elements with effective doping presents a number of difficulties for Al-rich AlGaN layers. 10 Degraded crystalline state is frequently perceived during the accumulation of Al-rich layers, which can be attributed to the foreign substrate's mismatch in lattice.…”