Abstract
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 265 nm 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.
•The position of the generated point defects in AlGaN-based LED chip is identified from the experiment.•Current stress induced point defects are located within the MQWs region, especially in the first QW near the p side.•These point defects density will cause the carrier redistribution in the active region.•The real characters of the generated point defects are investigated by DLTS spectra and TEM analysis.