Efficiency improvement of GaN-based light-emitting diodes by direct wet etching of indium-tin-oxide layer

The authors propose a simple direct wet etching method to texture the indium-tin-oxide (ITO) p-contact layer of GaN-based light-emitting diodes (LEDs). It was found that high density ITO nanorods with average diameter of 140 nm and average height of 120 nm were formed after the LED samples were immersed in a solution consists of HCl (30%), FeCl3 (30%) and de-ionised water (40%) for 2 min at room temperature. It was also found that output power of the LEDs with 2 min direct wet etching was 21% higher than that of conventional LEDs. Furthermore, it was found that such enhancement should be attributed to the enhanced photon extraction from the front surface of the LED chip.