High power InGaN/GaN flip-chip LEDs with via-hole-based two-level metallization electrodes

High power flip‐chip light‐emitting diodes with distributed n‐type via‐hole‐based two‐level metallization electrodes (TLM‐FCLED) were fabricated and investigated. Comparison tests altering Ni metal thickness and annealing temperature were performed to optimize the reflectivity of Ni/Ag reflective layer, which enhanced the light extraction efficiency. On the other hand, via‐hole‐based n‐contact electrodes structure increased the utilization ratio of active region area, and the introduction of first metallization layer allowed n‐contact to be arranged uniformly on the entire n‐GaN surface, which exhibited a more favorable current spreading uniformity. As a result, the light output power (LOP) of TLM‐FCLED was 9.23 and 26.55% higher than that of conventional high power LED (CHP‐LED) at 350 and 1050 mA. The CHP‐LED exhibited 13.39% external quantum efficiency (EQE) degradation from 350 to 1050 mA, whereas the TLM‐FCLED exhibited only 6.88% EQE degradation. It is noted that the maximum LOP was about 1264 mW at 1830 mA, thereby, suggesting the potential of its application in ultra‐high power applications.