Monolithic transfer of thin-film micro-LEDs via electrochemical etching

We report a scalable, low-damage, and high-throughput process for monolithic transfer of III-nitride micro-LED arrays using selective electrochemical etching and wafer bonding. A highly Si-doped n-GaN sacrificial layer enables rapid and uniform release while preserving device integrity, resulting in atomically smooth lift-off surfaces suitable for subsequent processing. Fully fabricated vertical micro-LED arrays with mesa sizes from 100 × 100 μm2 down to 3 × 3 μm2 are released and transferred to silicon carrier wafers in a single step, maintaining precise spatial registration without conventional laser lift-off or serial pick-and-place methods. Transferred devices exhibit low reverse leakage, uniform current injection and emission, and enhanced optical output due to the thin-film flip-chip architecture, with minimal degradation in spectral performance. This approach provides a promising pathway for the scalable heterogeneous integration of III-nitride devices for micro-displays, optical communications, and sensing applications.