The light extraction efficiency of p-GaN patterned InGaN/GaN light-emitting diodes fabricated by size-controllable nanosphere lithography

The authors present a light extraction improvement at a low operation voltage from p-GaN patterned InGaN/GaN light-emitting diodes (LEDs) fabricated using size-controllable nanosphere lithography and subsequent inductively coupled plasma etching. A 300-nm polystyrene (PS) nanosphere array was used as an etching mask in order to produce ordered pillar patterns on the p-GaN layer, during which the top and bottom size of the pillars were tailored to optimize the electrical and optical properties by varying the diameter of the PS nanosphere masks. Three LEDs, without patterns and with pillar patterns of 210 nm and 240nm diameter, were compared with each other, in which the LED with 240 nm diameter pillar patterns showed the highest output power (32.6% higher than that of the LEDs without patterns) in both its electroluminescence and photoluminescence measurements.