LAUSR

To improve the light extraction efficiency (LEE) of AlGaN-based deep ultraviolet LEDs (DUV-LEDs) by simple and effective method, this has greatly attracted ever-growing attention in DUV-LEDs field. Here, nanolens arrays (NLAs) fabricated by nanophotolithography and wet-etched technique is proposed to improve the LEE of DUV-LEDs, and its theoretical feasibility is verified by the Monte Carlo Ray-Trace method and finite element analysis which show an obvious improvement of light and electric field distribution benefit from NLAs structure. By controlling the time of wet etching, the effect of the uniform patterns of NLAs with adjustable morphology on the LEE of DUV-LEDs is systematically studied. Compared with the sandwiched flat lens, experimental results show that the obviously enhancements of the light output power are achieved by using the proposed NLAs to be 13.0%, 21.1%, 24.7%, 13.0%, and 11.5%, respectively, corresponding to their radius of 325, 340, 350, 360, and 400 nm, under the driving current of 300 mA. Therefore, the highest light output power of DUV-LEDs is used the optimized NLAs with radius of 350 nm, and its emission angle also shows the largest improvement of ~14°, suggesting the best LEE.