講演情報
[11a-S5-2]Enhanced Injection Efficiency in AlGaN-Based UVB Light-Emitting Diodes using Step-Graded Electron Blocking Layer
〇(PC)Muhammad Nawaz Sharif1, Hamida Zia1,2, Hideki Hirayama1 (1.RIKEN Japan, 2.Saitama University)
キーワード：
III-V nitrides semiconductors、Light Emitting Diode
AlGaN-based ultraviolet-B light-emitting diodes (UVB-LEDs) have emerged as a compelling alternative to conventional UV lamps, offering key advantages such as superior energy efficiency and extended operational lifetime. Despite these merits, the external quantum efficiency (EQE) of UVB-LEDs remains considerably lower than that of visible blue LEDs, which is primarily attributed to inadequate carrier injection into the active region and pronounced electron leakage into the p-type layers. Addressing these fundamental limitations is essential to advancing the practical deployment of AlGaN UVB-LEDs in applications. In this work, we systematically investigate the electron-blocking effect using single-, double-, and triple-layer electron-blocking layer (EBL) configurations in AlGaN-based UVB-LEDs. Our experimental results reveal that a single EBL is insufficient to confine carriers within the multiple quantum well (MQW) active region, leading to significant electron overflow and parasitic emission outside the intended active zone. By carefully engineering the barrier height in a double-layer EBL structure, carrier confinement is substantially improved by suppressing electron leakage, yielding a cleaner, single-peak emission spectrum. While introducing a third EBL layer further reduces electron leakage, it simultaneously impedes hole injection due to the increased effective barrier for hole transport, ultimately degrading the radiative recombination efficiency.
On-wafer characterization demonstrates that the double-layer EBL achieves a peak EQE of 3.0% with single-peak emission, outperforming both the single-layer EBL (2.3% EQE) and the triple-layer EBL (1.8% EQE). These findings highlight the trade-off between electron confinement and hole injection in multi-layer EBL designs and underscore the importance of balancing these competing effects.
On-wafer characterization demonstrates that the double-layer EBL achieves a peak EQE of 3.0% with single-peak emission, outperforming both the single-layer EBL (2.3% EQE) and the triple-layer EBL (1.8% EQE). These findings highlight the trade-off between electron confinement and hole injection in multi-layer EBL designs and underscore the importance of balancing these competing effects.