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 (μLEDs) with independent junction control. The cascaded μLEDs, consisted of blue μLEDs, a tunnel junction, and green μLEDs, were fully grown by metalorganic chemical vapor deposition. Blue, green, and blue/green emissions can be independently controlled in the same device. The blue μLEDs (60 × 60 μm2) and green μLEDs (40 × 40 μm2) exhibit a forward voltage of 4.1 and 3.1 V at 20 A/cm2 and a high peak external quantum efficiency of 42% and 14%, respectively. This demonstration paves the way for monolithic integration of full color cascaded μLEDs.