Structure and optical properties of GaN/metal/Si fabricated by laser lift-off and fusion bonding technique

GaN thin films grown on sapphire substrates are successfully bonded and transferred onto Si receptor substrates using fusion bonding and laser lift-off (LLO) technique. The GaN/Al₂O₃ structures are joined on Si substrates by pressure bonding Al/Ti/Au coated GaN surfaces onto Ti/Au/In coated Si receptor substrates at the temperature of 200°C. KrF excimer laser with 450 mJ/cm² energy density, 248 nm wavelength and 25ns pulse width is used to direct through the transparent sapphire substrates to separate GaN films from sapphire substrates. Scanning electron microscope (SEM) images show that compact GaN/Al/Ti/Au/In/Au/Ti/Si structures are formed during bonding process. Atomic force microscope (AFM) and photoluminescence (PL) measurements show that the qualities of GaN films on Si substrates degrade little after substrate transfer.