Hybrid Full-Color Inorganic Light-Emitting Diodes Integrated on a Single Wafer Using Selective Area Growth and Adhesive Bonding

In recent years, research into implementing microdisplays for use in virtual reality and augmented reality has been actively conducted worldwide. Specifically, inorganic light-emitting diodes (LED) have many advantages in microdisplays, so much effort has been made to implement them in various ways. However, it is still challenging to realize a display with high resolution using only inorganic LEDs without color conversion layers because a typical LED chip is designed to emit only one color on a single wafer. In this study, we integrated high-efficiency red, green, and blue (RGB) LED material systems on the same sapphire substrate. Since the blue and green LED structures comprised the same GaN semiconductor, a metalorganic chemical vapor deposition method was used to integrate them. Meanwhile, the red LEDs made from another semiconductor were incorporated into the blue/green LEDs using a wafer-bonding technique. The fabricated hybrid RGB LEDs were able to cover a wide color space. In addition, the RGB LED material systems consisting of a high-quality single crystal were stably combined on the sapphire substrate without any structural defects. We show the possibility of their use in displays by integrating the RGB LEDs on one chip and suggest that their utilization could range from large-area LED displays to ultrahigh-resolution small displays.