Monolithic integration of AlGaInP red and InGaN blue/green LEDs

Recently, microLED-based displays have been steadily developing and one of the technologies, the “RGB LED array monolithic integration” technology, has considerable prospects. This chapter introduces device manufacturing methods using only semiconductor patterning processes after bonding of red, green, and blue LEDs. These technologies are suitable for high-resolution applications such as AR/VR where it is hard to use a pick-and-place method. Here, various bonding technologies for color integration are reported: substrate bonding for two colors by wafer stacking, a method that realizes full color by combining a selective area growth method and a bonding technology, and a method that realizes full color using only a bonding technology. We also propose integration technologies using a monolithic 3D(M3D)-like process for high-resolution displays. We demonstrate ultra-high-resolution stacked LEDs exceeding 60,000 PPI estimated from their pattern size. Furthermore, we demonstrate one transistor-one photodiode M3D integration that has a clear readout operation without any degradation of the bottom Si devices after the integration process.