Structural and compositional characterization of MOVPE GaN thin films transferred from sapphire to glass substrates using chemical liftoff and room temperature direct wafer bonding and GaN wafer scale MOVPE growth on ZnO-buffered sapphire

摘要

GaN thin films were grown on ZnO/c-Al_2O_3 with excellent uniformity over 2 in. diameter wafers using a low temperature/pressure MOVPE process with N_2 as a carrier and dimethylhydrazine as an N source. 5 mm × 5 mm sections of similar GaN layers were direct-fusion-bonded onto soda lime glass substrates after chemical lift-off from the sapphire substrates. X-Ray Diffraction, Scanning Electron Microscopy and Transmission Electron Microscopy confirmed the bonding of crack-free wurtzite GaN films onto a glass substrate with a very good quality of interface, i.e. continuous/uniform adherence and absence of voids or particle inclusions. Using this approach, (In) GaN based devices can be lifted-ofT expensive single crystal substrates and bonded onto supports with a better cost-performance profile. Moreover, the approach offers the possibility of reclaiming the expensive sapphire substrate so it can be utilized again for growth.