Etching-free pixel definition gives 10 µm green micro-LEDs 6.48% on-wafer peak efficiency
What was demonstrated
Research arrays of InGaN green micro-LEDs with 50, 30 and 10 µm pixels were made using selective thermal oxidation, a method that defines pixels without plasma etching. The 10 µm array reached a peak on-wafer external quantum efficiency of about 6.48%, which the main text reports at 0.4 mA. Peak efficiency fell with pixel size (8.02%, 7.79% and 6.48% for 50, 30 and 10 µm at 0.4 mA). Its leakage current density was 1.2 × 10⁻⁶ A/cm² at -10 V after 4 hours of air annealing with a 3.5 µm SiO2 layer. The authors describe this leakage as at a relatively low level compared with micro-LEDs made using conventional plasma etching and dielectric passivation, citing values reported in other studies.
Why it matters
Plasma etching can damage pixel sidewalls, and that damage takes up a larger share of the emitting area as pixels shrink, which is an obstacle for dense microLED displays. This work shows a way to define small green pixels without plasma etching. It is shown on research arrays and has not been built into a display.
Caveats
- This is a research array on the wafer, not a display product. The 6.48% figure applies to the 10 µm array only and is quoted at 0.4 mA.
- The leakage comparison with conventional plasma-etched micro-LEDs relies on values reported in other studies.
- Longer annealing raised the working voltage, oxygen spread about 300 nm under the SiO2 mask, and the oxide mask occasionally peeled off. Cracks about 950 nm long formed near the oxide and LED interface, which the authors note could matter more for smaller devices.
Technology profiles
Sources
- peer reviewed paper
Etching-free pixel definition in InGaN green micro-LEDs
Zhiyuan Liu, Yi Lu, Haicheng Cao et al.. Light: Science & Applications, 24 May 2024. DOI: 10.1038/s41377-024-01465-7.
Last reviewed 21 Oct 2026.