Abstract: Gallium Nitride film was successfully separated from sapphire substrate by laser radi-ation. The absorption of the 248nm radiation by the GaN at the interface results inrapid thermal decomposition of the interfacial layer, yielding metallic Ga and N2 gas.The substrate can be easily removed by heating above the Ga melting point (29℃).X-ray diffraction, atomic force microscopy and Photoluminescence of GaN before andafter lift-off process have been performed, which demonstrated that the separation andtransfer process do not alter the structural quality of the GaN films. And further dis-cussions on the threshold energy and crack-free strategies of laser lift-off process havealso been presented.

Key words: GaN, lift-off, freestanding, photoluminescence, X-ray diffrac tion, atomic force microscopy