In this study, III-nitride red micro-light-emitting diodes (µLEDs) with ultralow forward voltage are demonstrated on a strain relaxed template. The forward voltage ranges between 2.00 V and 2.05 V at 20 A/cm2 for device dimensions from 5 × 5 to 100 × 100 µm2. The µLEDs emit at 692 nm at 5 A/cm2 and 637 nm at 100 A/cm2, corresponding to a blueshift of 55 nm due to the screening of the internal electric field in the quantum wells. The maximum external quantum efficiency and wall-plug efficiency of µLEDs are 0.31% and 0.21%, respectively. This suggests that efficient III-nitride red µLEDs can be realized with further material optimizations.
