On-Chip Integration of III-Nitride Flip-Chip Light-Emitting Diodes With Photodetectors

The fabrication of GaN light-emitting diodes (LEDs) with on-chip photodetectors (PDs) based on flip-chip configuration is reported. The exposed sapphire plays a key role not only in light extraction but also light guiding in the lateral direction. The same InGaN/GaN quantum well structure responsible for light emission in the LED and photodetection in the PD is characterized. The light-detecting mechanism of on-chip PDs at varying positions are also studied and verified by simulation. Compared with the design of PD adjacent to the LED, the PD formed in the center of the LED has less influence on the uniformity of the LED emission, and exhibits one-third increase in photocurrent. The flip-chip packaging device also enables a yellow phosphor film to be directly integrated onto the sapphire surface to generate white light emission. The on-chip PD is capable of detecting the variation of LED intensity without blocking the light output emission, which makes it highly valuable for real-time detection of the intensity of LED sources in various lighting applications.