Fabrication of GaN epitaxial thin film on InGaZnO4 single-crystalline buffer layer

Epitaxial (0001) films of GaN were grown on (111) YSZ substrates using single-crystalline InGaZnO4 (sc-IGZO) lattice-matched buffer layers by molecular beam epitaxy with a NH3 source. The epitaxial relationships are (0001)GaN//(0001)IGZO//(111)YSZ in out-of-plane and [112¯0]GaN//[112¯0]IGZO//[11¯0]YSZ in in-plane. This is different from those reported for GaN on many oxide crystals; the in-plane orientation of GaN crystal lattice is rotated by 30° with respect to those of oxide substrates except for ZnO. Although these GaN films showed relatively large tilting and twisting angles, which would be due to the reaction between GaN and IGZO, the GaN films grown on the sc-IGZO buffer layers exhibited stronger band-edge photoluminescence than GaN grown on a low-temperature GaN buffer layer.