Electronic Transport Properties of Monocrystalline ZnO-Plate Synthesized by Chemical Vapor Transport Deposition

The large-sized monocrystalline ZnO-plate(25 mm×25 mm×7 mm),an advanced laser material,was synthesized by chemical vapor transport deposition on the fairly cheap substrate of sapphire pre-coated with epitaxial GaN(0002)transition-layer.The non-homogeneous depth distributions of the microstructures,phase-structures and electric transport behavior was studied with X-ray diffraction,energy dispersive spectroscopy,scanning electron microscopy and time-of-flight secondary ion mass spectroscopy.The results show that the top-layer of quasi intrinsic ZnO-semiconductor coexisted with the bottom-layer of quasi degenerated ZnO-semiconductor,because of the great variations in the crystallinity and purity.Specifically,as the top-down depth increased,when measured at 300 K the dislocation density and Ga/Li/Na/K/Si-impurity densities increased,resulting in the significant decreases of resistivity and carrier-mobility,and bringing about a considerable increase of carrier concentration.We suggest that the synthesized bulk ZnO-material be of some technological interest in fabrication of photoelectric devices.