Heterogeneous Growth of ZnO Crystal on GaN/Al2O3 Substrate

Hydrothermal (HT) ZnO substrates were usually used as seeds for the vapor growth of ZnO crystals. In this work, ZnO bulk crystals were grown using the relatively low-cost GaN/Al2O3 substrates as seeds by chemical vapor transport (CVT). With the increase of growth time, the dislocation densities in the crystal decreased from about 1x10(6) to 6x10(3) cm(-2). The carrier concentration decreased from 1.24x10(19) to 1.57x10(17) cm(-3), while the carrier mobility increased from 63.8 to 179 cm(2)/(V center dot s). The optical transmittance in the VISNIR wavelength increased significantly in combination with the decreasing dislocation densities and impurity concentrations. The dislocation lines and related fast diffusion paths gradually decreased and disappeared in the late growth stage, and the crystal qualities were consequently improved. The experimental results show that the properties of as-grown ZnO crystals are comparable with bulk ZnO grown on the HT substrates to some extent. The GaN/Al2O3 seeds may have a potential application value in the industrial production of ZnO single crystals.

Automated summary

ZnO bulk crystals were grown using low-cost GaN/Al2O3 substrates as seeds by CVT. The crystal quality was improved with decreasing dislocation densities and impurity concentrations. The carrier concentration decreased and carrier mobility increased with the increase of growth time. The findings suggest that GaN/Al2O3 seeds have potential application value in the industrial production of ZnO single crystals.