Electrochemical potentiostatic activation for improvement of internal quantum efficiency of 385-nm ultraviolet light-emitting diodes

The electrochemical potentiostatic activation (EPA) method is proven to effectively improve the internal quantum efficiency (IQE) of 385-nm ultraviolet light-emitting diodes (UV-LEDs). UV-LEDs wafers were immersed into 1.0 M HCl solution, and an electric voltage of 3.0 V was applied to the p-type GaN layer in order to increase the hole concentration by breaking the MgH complex. Secondary ion mass spectroscopy analysis clearly indicates the successful removal of hydrogen atoms by the EPA process, which is a ∼35% reduction of the hydrogen concentration compared to the conventional N2 annealing. The light-output power was enhanced by ∼20% at an input current of 50 mA, which originated from an improvement of the IQE by ∼20%. The reverse leakage current was also lowered by about one order after the EPA process.