AlGaN-based deep ultraviolet LEDs with high Al composition are promising for many applications, including air-or water-purification, fluorescence sensing, etc. However, to realize their full potential, it is important to understand the impact of the point defects on the device performance. Here, we investigate the defects in the 265nm AlGaN-based deep ultraviolet LEDs after degradation systematically with a combination of different analytical technologies. The results show that point defects increase after the degradation. The generated defects during the stress lead to a carrier redistribution in the active region and the induced point defects during the degradation are located within the multi-quantum wells (MQWs) region, especially in the first quantum well near the p side of the LED chip. The dislocation lines in the MQWs region were also observed after the degradation, which can lead to the Mg diffusion along the dislocation line. These findings are important to understand the defects in AlGaN quantum wells and further improve AlGaN-based deep ultraviolet LEDs' performance.

Investigation of the immunological effect of light-up carbon-dots on cancer-bearing mice.

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