Light output improvement of 10 W operated vertical LEDs via surface roughening using a commercialized developer

We report improvement of improvement effectiveness of the light extraction efficiency of 10 W operated InGaN-based vertical light-emitting diodes via n-GaN surface roughening, using a commercial photoresist (PR) developer as an etching solution, which was compared with a conventional KOH-based solution. With the conventional KOH-based solution for n-GaN surface roughening, although both the depth and density of the etch pyramid initially increased with etching time, the depth eventually decreased and the density also decreased gradually, resulting in degradation in improvement effectiveness of extraction efficiency. Using the commercial PR developer for etching, however, after an initial increase in both the depth of the etch pyramid and its density, the depth and density were maintained without degradation, confirming the improvement in improvement effectiveness of extraction efficiency as well as the improvement in run to run fabrication uniformity. This may be due that with developer the GaN surface is etched only along the dislocation and is not etched over the non-defect region even as etching time goes on.