Analysis of the efficiency improvement of 273 nm AlGaN UV-C micro-LEDs

UV-C LEDs have great application prospects in the fields of sterilization, disinfection, and non-line-of-sight solar-blind communication. However, their efficiency is currently not high enough to satisfy these applications and needs to be improved. In this work, AlGaN based UV-C LEDs (273 nm) with size from 8 to 200 mu m were fabricated to evaluate the size effect of external quantum efficiency (EQE). Higher EQE was detected in smaller-size UV-C micro-LEDs. Simulations on EQE were performed. The analysis on experimental data and the simulation results reveals that higher EQE originates from both higher internal quantum efficiency at high current densities due to better current spreading and higher light extraction efficiency (LEE) due to the larger proportion of sidewall. From the efficiency improvement mechanism, it is concluded that the most sever current density non-uniformity and LEE loss of UV-C devices compared with visible or near ultraviolet LEDs can be effectively restrained by preparing micro-LEDs. Our work helps to optimize the efficiency characteristics for UV-C applications.

Automated summary

This study found that AlGaN-based small-sized UV-C micro-LEDs have higher external quantum efficiency (EQE). Simulations showed that the higher EQE comes from better current spreading and higher light extraction efficiency (LEE) due to a larger proportion of sidewall. The use of small-sized UV-C micro-LEDs effectively addresses the current density non-uniformity and LEE loss issues in UV-C devices.