Selective lift-off of GaN light-emitting diode from a sapphire substrate using 266-nm diode-pumped solid-state laser irradiation

Abstract

Selective laser lift-off of GaN from a sapphire substrate was demonstrated using 266-nm diode-pumped solid-state laser irradiation. To fabricate a single GaN light-emitting diode (LED) with a size of 100 μm × 100 μm, we used a simple direct scanning technique with a defocused beam and investigated the lift-off parameter in terms of the intensity. Two processing windows corresponding to lower- and higher-intensity regimes were observed experimentally. In the lower-intensity regime, the larger beam size worked better than with the higher regime. Although fluence is generally explained as a processing condition, the total input fluence for a single LED was not crucial to lift-off in case of the scanning technique using a defocused laser beam. However, an intensity of ~37 kW/cm² was required to initiate the thermal decomposition reaction in GaN at any sample position.