Damage-Free Transfer of GaN-Based Light-Emitting Devices and Reuse of Sapphire Substrate

Abstract

Gallium nitride (GaN) based semiconductors have been gaining worldwide attention in optoelectronics application, notably information displays and solid-state lighting. GaN light-emitting diodes (LEDs) epilayers are typically grown on sapphire substrates with metal-organic chemical vapor deposition (MOCVD) technique due to the absence of native nitride substrates. In this paper, the mesh-patterned sapphire substrates are fabricated to speed up the laser lift-off efficiency for the separation of GaN films from sapphire substrates. Damage-free GaN thin films fabricated on the sapphire substrates were successfully released and transferred onto Si substrates with sufficient quality through a Ti/Pt/Au/In bonding and subsequent laser lift-off processes. The GaN film mounted on Si substrates exhibits almost no attenuation in PL intensity before and after its transfer. The released sapphire substrate can be reprocessed by annealing & chemical mechanical polishing (CMP) process for reuse as epitaxial substrate with considerable cost reduction, featuring a comparable photoluminescence performance with fresh sapphire substrates.