GaN-Based LEDs With Omnidirectional Metal Underneath an Insulating ${\rm SiO}_{2}$ Layer

The authors report GaN-based light-emitting diodes (LEDs) with an Ag layer underneath an insulating SiO₂ layer. It was found that we can not only achieve much better current spreading, but also prevent the light absorption by the opaque p-pad electrode. With 20-mA current injection, it was found that the output power of the LEDs with SiO₂/Ag layers was 4.1% and 9.6% larger than those of the LEDs with a SiO₂ layer and the LEDs without a SiO₂ layer, respectively. It was also found that the 20-mA forward voltage only increased slightly, from 3.03 to 3.05 V, for the LEDs with the SiO₂/Ag layers.