High Wall-Plug Efficiency AlGaN Deep Ultraviolet Micro-LEDs Enabled by an Etched Reflective Array Design for High Data Transmission

AlGaN deep ultraviolet light-emitting diodes (DUV LEDs) have potential applications in free-space communication, but their current limited efficiency restricts the further development of free-space ultraviolet communication (FSUC) applications. In this work, an etched reflective array (ERA) strategy has been proposed in DUV micro-LEDs with various pixel sizes of 20, 30, and <inline-formula> <tex-math notation="LaTeX">$60~\mu \text{m}$ </tex-math></inline-formula>, to enhance the efficiency via etching the p-GaN layer to reduce light absorption and fabricating full-spatial omnidirectional reflector (FSODR) to increase light extraction. The 20-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> DUV micro-LEDs with ERA strategy exhibit a light output power (LOP) of 39.9 mW at 160 mA and a record high wall-plug efficiency (WPE) of 8.3% at 5 mA. Critically, both the transverse-magnetic (TM) and transverse-electric (TE) mode light intensity are significantly enhanced by 52.59% and 46.29%, respectively, compared with the device without ERA strategy. Furthermore, simulation results show that the light extraction efficiency (LEE) of TM- and TE-polarized light for the 20-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> DUV micro-LEDs with ERA strategy are enhanced by 48.66% and 46.05%, respectively. In addition, this device achieves a high data transmission rate of 3.819 Gbps in FSUC.