Performance enhancement by different sidewall structures for InGaN-based light-emitting diodes

Abstract

We demonstrate high-performance GaN-based light-emitting diodes (LEDs) using different sidewall structure. The patterned pyramidal sidewall (PPS) structure in LED is fabricated by crystallographic etching process, which is applying hot phosphoric acid wet etching at the GaN/Al2O3 interface after normal front-side laser scribing. To obtain continuous, regular and bigger pyramidal sidewalls we applied higher temperature and longer time on the LEDs. However, there might be negative effect on the reliability of the PPS-LED by the higher experimental conditions. On the other hand, we applied the new stealth dicing process to form the clean and non-destructive sidewalls. The three times stealth dicing process can get a better well-distributed and shipshape sidewall than one time stealth dicing. The light output power of the PPS-LED had a 39.6 % enhancement compared to the standard LED owing to the larger light-scattering when measured in LED chip form. But the LED with stealth dicing is more reliable than PPS-LED regardless of the crystal quality of the LED.