Improvement of leakage current and optical properties of GaN-based LEDs by chemical etching of p-GaN

A chemical etching using a molten KOH+NaOH solution was developed to improve optical properties and leakage current of GaN light-emitting diodes (LEDs). The Photoluminescence (PL), capacitance-voltage (C-V) and currentvoltage (I-V) analysis showed that deep donor-acceptor pair (DDAP) defects were effectively removed by the chemical etching process. As a result, the forward and reverse leakage current of etched GaN LEDs were greatly decreased due to the reduced DDAP defects. The light output power of etched GaN LEDs was significantly improved by 45 % at an injection current of 20 mA due to the increased surface roughness of the p-GaN after the chemical etching. Furthermore, the light output power of etched GaN LEDs was saturated at an injection current of 340 mA compared to that of nonetched GaN LEDs which was saturated at 300 mA. In addition, the red-shift of electroluminescence (EL) peak wavelength in etched GaN LEDs was much smaller than that of non-etched GaN LEDs due to the suppression of Jouleheating by removal of DDAP defects.