Investigation of quantum structure in N-polar deep-ultraviolet light-emitting diodes

This study systematically investigates the optical performance of N-polar deep-ultraviolet light-emitting diodes (DUV LEDs) in consideration of different quantum structures in the active region, with a highlight on various thicknesses of quantum barrier (QB), quantum well (QW), and the electron-blocking layer (EBL). The results show that the internal quantum efficiency (IQE), as well as light output power (LOP) of N-polar DUV LED, is not sensitive to QB thickness. On the contrary, the LOP and IQE performance can be significantly enhanced by increasing the QW thickness from 2 to 4 nm. Moreover, a saturated LOP in the N-polar DUV LEDs can be observed after QW thickness increased to a certain level as there is a trade-off between boosted carrier concentration and decreased wave function overlap in the active region. Lastly, the impact of the EBL on the optical performance of the N-polar DUV LED is also investigated. Specifically, a thicker EBL or a higher Al composition in the EBL leads to an increase in the turn-on voltage and series resistance while the LOP value remains unchanged. These findings lay the foundation for the development of high-performance N-polar DUV LEDs of the future.