InGaN-based red micro-light-emitting diodes for display applications

The emerging InGaN-based red light-emitting diodes (LEDs) are promising candidates for display applications due to their potential high efficiency. In this work, we first investigated the electrical and optical properties of InGaN red LEDs on sapphire with various chip sizes (from 500×500 to 15×15 µm2). By detailed characterization on the current-voltage measurement and current dependent light output power measurement, the negligible size-dependent effect was revealed. The suppressed surface recombination effect may be due to the effective carrier trapping effect by the V-pits, which prevents the carriers from flowing to the sidewalls. Furthermore, we developed releasing techniques for the InGaN red LEDs on silicon, enabling the integration via micro-transfer printing. The device performance after transfer printing was characterized in detail. The integration of red, green and blue InGaN-based micro-LEDs via micro-transfer printing were successfully demonstrated. This work paved the way for integrating InGaN red LEDs in the displays for higher performance.