Gallium Nitride film was successfully separated from sapphire substrate by laser radiation. The absorption of the 248 nm radiation by the GaN at the interface results in rapid thermal decomposition of interfacial layer, yielding metallic Ga and N2 gas. The substrate can be easily removed by heating above the Ga melting point (29°C). X-ray diffraction, atomic force microscopy and photoluminescence of GaN before and after lift-off process have been performed, which demonstrated that the separation and transfer process do not alter the structural quality of the GaN films. And further discussions on the threshold energy and crack-free strategies of laser lift-off process have also been presented.
J. Xu, R. Zhang, Y.P. Wang, X.Q. Xiu, S.L. Gu, B. Shen, Y. Shi, Z.G. Liu and Y.D. Zheng (Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China)
