Enhancing the optical and electrical properties of AlGaN ultraviolet-C micro-LED via a hybrid scheme of plasma and chemical treatment

Ultraviolet band C (UV-C) micro light-emitting diodes (micro-LEDs) provide a high energy light emission of 200-280 nm, which are brilliantly utilized in optogenetics, communications, and fluorescence. However, the limited device efficiency notably restricts the grand potential application field. In this work, three types of 20 x 20 mu m(2) UV-C micro-LEDs with the peak wavelength of 269 nm are fabricated by different etching strategies, including an inductively coupled plasma (ICP), post-ICP tetramethylammonium hydroxide, and a hybrid scheme combining plasma and chemical treatment. By enhancing the radiative recombination and light extraction, the hybrid scheme improves the peak external quantum efficiency of UV-C micro-LEDs to 3.45%, an elevation of 57.5% compared with ICP. A step advance in the forward injection current and ideality factor is also found on the devices fabricated by the hybrid scheme due to better contact on the AlGaN surface.