Improvement in light-output power of InGaN/GaN light-emitting diodes by p-GaN surface modification using self-assembled metal clusters

摘要

To improve the escape of photons from an LED structure, we fabricated nano-sized cavities on a p-GaN surface utilizing Pt self-assembled metal clusters for an etch mask. Wet and dry etching processes were employed to produce nano-sized cavities on the p-GaN surface. The dry etching process produced cavities with diameters ranging from 200 nm to 450 nm and from 30 to 80 nm in depth, respectively. The wet etching process, however, produced small size cavities with a size of 5 ～ 6 nm. Electroluminescence measurement showed that the relative optical output powers are increased by 88 % as evidenced by frontside measurement compared to those of LEDs with no nano-sized cavities. In addition, the electrical performance was also improved as evidenced by the Ⅰ-Ⅴcharacteristic curves. This enhanced performance can be attributed to an enhancement in light escaping due to the increased light emitting area as the result of the surface cavities and also to the reduced contact resistance due to the increased contact area.