Zinc oxide (ZnO) single crystals were grown by the hydrothermal method using lithium and potassium hydroxide as mineralizer and properties of the grown crystals were characterized from the viewpoints of epitaxial wafer applications. The growth sector dependence of impurity and defect concentrations were characterized by secondary ion mass spectroscopy and photoluminescence. As a result, it was clearly shown that defect and impurity distribution in the obtained crystal was anisotropic, and this anisotropy is affected by the choice of the seed crystal shape and growth direction. Annealing effect on flatness of the wafer surface was also examined, and it was found that high temperature annealing with flat single crystalline cover is appropriate for removal of scratch and formation of atomically flat surface. Moreover, we show the possible miss-evaluation of Hall coefficient of ZnO due to anisotropy in defects and impurities distributions.