Performance enhancements in optoelectrical properties of InGaN/GaN light-emitting diodes with micro-hole arrayed indium-tin-oxide layer

We demonstrated that the InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) with micro-hole arrays exhibit better performance in optoelectrical properties than do the conventional LEDs. With injection current of 20 mA, by employing the micro-hole array on top surface of the LED structure, the room-temperature output power conversion efficiency and external quantum efficiency were increased 28.7% and 14.3%, respectively, compared with the conventional broad area devices. From room temperature I-V characteristics of the LEDs, it has found that series resistance and leakage current were related with hole dimensions and etching depths, respectively. Interestingly, the leakage current of the transparent conductive layer (TCL) was dominated by the contribution of the micro-hole side-wall, the number of the etching micro-holes, and the wet-etched depths. We conclude that a well-designed micro-hole array structure can indeed significantly not only inhibit the leakage current of ITO transparent conductive layer, but also enhance external quantum efficiency and extraction efficiency by using wet etching process, over a broad temperature ranges.