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.

Designing an Ultrathin Film Spectrometer Based on III-Nitride Light-Absorbing Nanostructures

“…As a result, the proposed pss as a wafer-scale light trapping structure can be fairly economical to manufacture. In the current design, we consider the pattern to be fabricated on the bottom side of the sapphire substrate, as a laser lift-off (LLO) process to separate the GaN layer from the pss substrate is still in development [ 32 ]. In the future, it may be possible for the photodiode epitaxial stack to be grown directly on a pss, which can then be coated from the underside with a metal back-reflector after substrate removal.…”