Mechanism Underlying Damage Induced in Gallium Nitride Epilayer during Laser Lift-Off Process

Abstract

A vertical-type gallium nitride blue light-emitting diode on silicon was prepared by using a laser lift-off process. A grid like surface was obtained after the laser lift-off process. The central part of the grid preserves a uniform surface morphology, but damage occurred and a crack was formed on the peripheral area of a grid. Though a comparison of the crystalline and optical properties of the central and peripheral areas, the high thermal gradient of the peripheral area under pulse laser shot irradiation was found to play an important role during the laser lift-off process.