DAMAGE-FREE SEPARATION OF GAN THIN-FILMS FROM SAPPHIRE SUBSTRATES

Gallium nitride thin films grown on sapphire substrates were successfu lly separated and transferred onto Si substrates using single 38 ns Kr F excimer laser pulses directed through the transparent substrate at f luences in the range of 400-600 mJ/cm(2). The absorption of the 248 nm radiation by the GaN at the interface induces rapid thermal decomposi tion of the interfacial layer, yielding metallic Ga and N-2 gas. The s ubstrate is easily removed by heating above the Ga melting point of 30 degrees C. Scanning electron microscopy and x-ray diffraction of the GaN films before and after lift-off demonstrate that the structural qu ality of the GaN films is not altered by the separation and transfer p rocess. (C) 1998 American Institute of Physics.