Increase in the efficiency of III-nitride micro LEDs by atomic layer deposition.

The effect of atomic-layer deposition (ALD) sidewall passivation on the enhancement of the electrical and optical efficiency of micro-light-emitting diode (µ-LED) is investigated. Various blue light µ-LED devices (from 5 × 5 µm to 100 × 100 µm) with ALD-AlO sidewall passivation were fabricated and exhibited lower leakage and better external quantum efficiency (EQE) comparing to samples without ALD-AlO sidewall treatment. Furthermore, the EQE values of 5 × 5 and 10 × 10 µm devices yielded an enhancement of 73.47% and 66.72% after ALD-AlO sidewall treatments process, and the output power also boosted up 69.3% and 69.9%. The Shockley-Read-Hall recombination coefficient can be extracted by EQE data fitting, and the recombination reduction in the ALD samples can be observed. The extracted surface recombination velocities are 551.3 and 1026 cm/s for ALD and no-ALD samples, respectively.