Optimized via-hole structure in GaN-based vertical-injection light-emitting diodes

This study examined the electrical and the optical characteristics of GaN-based vertical-injection light-emitting diodes (VI-LEDs) with various numbers of via holes. As the number of via holes was increased from 1 to 11, the operating voltage at 350 mA of the VI-LEDs decreased from 5.4 to 3.7 V, and the light output power increased greatly from 150 to 233 mW. A further increase in the number of via holes up to 23, however, decreased the light output power due to a decrease in the active area, which resulted in an increase in the efficiency droop at high current injection. The light intensity distributions were characterized by using beam profile measurements to assess the current crowding phenomenon of the VI-LEDs according to the number of via holes. The VI-LEDs with 1 and 5 via holes exhibited a non-uniform light intensity distribution whereas the VI-LEDs with 11 via holes displayed a uniform light intensity distribution and an improved efficiency droop due to the current being uniformity spread by the adequate number of via holes, which suggests that in this study, the VI-LEDs with 11 via holes are optimized via the hole structures.