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 µm² to 100 × 100 µm²) with ALD-Al₂O₃ sidewall passivation were fabricated and exhibited lower leakage and better external quantum efficiency (EQE) comparing to samples without ALD-Al₂O₃ sidewall treatment. Furthermore, the EQE values of 5 × 5 and 10 × 10 µm² devices yielded an enhancement of 73.47% and 66.72% after ALD-Al₂O₃ 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.