Laser lift-off of GaN thin film and its application to the flexible light emitting diodes

Abstract

The high performance GaN light emitting diode (LED) from sapphire wafer has been transferred on a plastic substrate with 308nm XeCl laser lift-off (LLO) for next generation flexible lighting applications. SU-8 passivation with thermal release tape (TRT) adhesive enables structure coverage and adhesion so that it can be an excellent candidate for a carrier substrate for non-wetting transfer process using laser liftoff technology. The dimensions of the laser beam are also investigated in two types (3μm x 5cm and 1.2mm x 1.2mm) to reduce stress when decomposition of GaN occurs. With careful optimization of carrier substrate and laser beam conditions, we can fabricate flexible GaN LED on polyimide substrates which shows similar electrical properties to the GaN LED on bulk sapphire substrate.