INTEGRATION OF GaN THIN FILMS WITH DISSIMILAR SUBSTRATE MATERIALS BY Pd-In METAL BONDING AND LASER LIFTOFF

GaN thin films grown on sapphire substrates were successfully bonded and transferred onto GaAs, Si, and polymer "receptor" substrates using a low-temperature Pd-In bond followed by a laser lift-off (LLO) process to remove the sapphire growth substrate. The GaN/sapphire structures were joined to the receptor substrate by pressure bonding a Pd-In bilayer coated GaN surface onto a Pd coated receptor substrate at 200 C. XRD showed that the intermetallic compound PdIn3 formed during the bonding process. LLO, using a single 600 mJ/cm2, 38 ns KrF (248 nm) excimer laser pulse directed through the transparent sapphire substrate, followed by a low- temperature heat treatment, completed the transfer of the GaN onto the "receptor" substrate. Cross-sectional SEM and X-ray rocking curves showed that the film quality did not degrade significantly during the bonding and LLO process. 17 refs.