Advantages of AlGaN-based deep ultraviolet light-emitting diodes with graded quantum structures in the active region

AlGaN-based deep ultraviolet light-emitting diode (DUV LED) performance is far from satisfaction for commercialization owing to its poor external quantum efficiency, low hole injection efficiency, and large current leakage, etc. In our works, we investigated several DUV LEDs with special multi-quantum wells (MQWs) structures, including graded quantum wells (QWs) for mitigating the quantum confined Stark effect and graded quantum barriers (QBs) for enhancing the electron blocking capability as well as hole injection efficiency. We found that these unique MQW structures could remarkably improve the internal quantum efficiency, external quantum efficiency and light output power. The proposed structure with such promising graded QWs or graded QBs provides us an effective solution to boost optical power in the pursuit of high-performance DUV emitters.