Investigation of high extraction efficiency flip-chip GaN-based light-emitting diodes

In order to obtain higher light output power, the flip-chip structure is used. We studied the ratio of the light of GaN sides before and after fabricating metal reflector on p-GaN. The SiO2/SiNx dielectric film reflectors were deposited through plasma enhance chemical vapor deposition following the fabrication of metal reflector, and then the dielectric film reflectors on the electrodes were etched in order to expose the electrodes to the air. It is found that comparing with the flip-chip GaN-LED without dielectric film reflectors, light output power can be increased by as high as 10.2% after the deposition of 2 pairs of SiO2/SiNx dielectric film reflectors on GaN-LEDs, which cover the sidewalls and the areas without the metal reflector. This result indicates that the high reflector formed by multi-layer dielectric films is useful to enhance the light output power of GaN-based LED, which reflects light from step sidewalls and p-GaN without metal reflector to internal, and then light emits from the surface.