scholarly journals Improved Performance of Electron Blocking Layer Free AlGaN Deep Ultraviolet Light-Emitting Diodes Using Graded Staircase Barriers

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 334
Author(s):  
Barsha Jain ◽  
Ravi Teja Velpula ◽  
Moulik Patel ◽  
Sharif Md. Sadaf ◽  
Hieu Pham Trung Nguyen

To prevent electron leakage in deep ultraviolet (UV) AlGaN light-emitting diodes (LEDs), Al-rich p-type AlxGa(1−x)N electron blocking layer (EBL) has been utilized. However, the conventional EBL can mitigate the electron overflow only up to some extent and adversely, holes are depleted in the EBL due to the formation of positive sheet polarization charges at the heterointerface of the last quantum barrier (QB)/EBL. Subsequently, the hole injection efficiency of the LED is severely limited. In this regard, we propose an EBL-free AlGaN deep UV LED structure using graded staircase quantum barriers (GSQBs) instead of conventional QBs without affecting the hole injection efficiency. The reported structure exhibits significantly reduced thermal velocity and mean free path of electrons in the active region, thus greatly confines the electrons over there and tremendously decreases the electron leakage into the p-region. Moreover, such specially designed QBs reduce the quantum-confined Stark effect in the active region, thereby improves the electron and hole wavefunctions overlap. As a result, both the internal quantum efficiency and output power of the GSQB structure are ~2.13 times higher than the conventional structure at 60 mA. Importantly, our proposed structure exhibits only ~20.68% efficiency droop during 0–60 mA injection current, which is significantly lower compared to the regular structure.

2019 ◽  
Vol 56 (6) ◽  
pp. 060001
Author(s):  
田康凯 Tian Kangkai ◽  
楚春双 Chu Chunshuang ◽  
毕文刚 Bi Wengang ◽  
张勇辉 Zhang Yonghui ◽  
张紫辉 Zhang Zihui

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Hongfeng Jia ◽  
Huabin Yu ◽  
Zhongjie Ren ◽  
Chong Xing ◽  
Zhongling Liu ◽  
...  

Abstract An aluminum-rich AlGaN layer is commonly implemented to act as an electron-blocking layer (EBL) to block electron overflow from the active region in the conventional deep-ultraviolet light-emitting diodes (DUV LEDs). Herein, we propose a DUV LED device architecture with specially designed band-engineered quantum barriers (QBs) to “serve” as an alternative approach to alleviate such overflow effect, suppressing the electron leakage, and facilitating the electron and hole injection into the active region for efficient radiative recombination. Intriguingly, a much smaller efficiency droop with a significant enhancement of light output power (LOP) by nearly 50% can be achieved at the injection current level of 120 mA in such EBL-free device, in comparison with the conventional EBL-incorporated DUV LED structure. Thus, the EBL-free device architecture provides us an alternative path toward the realization of efficient DUV light emitters.


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