Damage-Free Organic Passivation Layer for Improved Optical and Electrical Performance of InGaN/GaN Blue Micro-LEDs

Micro light-emitting diodes (μ-LEDs) are widely adopted in high-performance display applications due to their exceptional efficiency, brightness, and stability. However, as the chip size decreases, the external quantum efficiency (EQE) of μ-LEDs significantly declines due to sidewall defects primarily caused by plasma reactive ion etching. In this study, a novel passivation strategy is proposed for μ-LEDs using an organic passivation layer, poly(1,3,5-trimethyl-1,3,5-trivinyl-cyclotrisiloxane) (pV3D3). The passivation layer is conformally deposited using initiated chemical vapor deposition (iCVD) under plasma-free and solvent-free environment at near-room temperature (40 °C). The impact of pV3D3 passivation on the optical and electrical performance of μ-LEDs is thoroughly investigated and compared with that of a conventional Al₂O₃ passivation layer deposited via thermal atomic layer deposition. The μ-LEDs (20 × 20 µm²) with pV3D3 passivation achieved a 235% higher photoluminescence intensity, 177% higher electroluminescence intensity at 0.1 A cm⁻², and 61% higher peak EQE compared with the Al₂O₃ passivation layer. Thus, the plasma-free, solvent-free, and low-temperature iCVD process improves the performance of μ-LEDs.