Demonstration Of High Efficiency Cascaded Blue And Green Micro-Light-Emitting Diodes With Independent Junction Control

We demonstrate efficient cascaded blue/green micro-size light-emitting diodes (mu LEDs) with independent junction control. The cascaded mu LEDs, consisted of blue mu LEDs, a tunnel junction, and green mu LEDs, were fully grown by metalorganic chemical vapor deposition. Blue, green, and blue/green emissions can be independently controlled in the same device. The blue mu LEDs (60x60 mu m(2)) and green mu LEDs (40x40 mu m(2)) exhibit a forward voltage of 4.1 and 3.1V at 20A/cm(2) and a high peak external quantum efficiency of 42% and 14%, respectively. This demonstration paves the way for monolithic integration of full color cascaded mu LEDs.