Mechanism of zinc oxide single crystal growth under hydrothermal conditions

The growth mechanism of ZnO single crystals is discussed on the basis of the analysis of ZnO crystal structure and physical-chemical characteristics of growth media. Polar growth of ZnO single crystals along the C-axis is explained taking into account the mechanism of the interaction between negatively charged Zn-containing species in the solution and the (0001), (000 (1) over bar) surfaces with different chemical compositions (Zn-flat plane for the face of positive mononedron, O-flat plane for the face of negative monohedron) and the opposite sign of the charge (close to +2 and -2 respectively). Partial substitution of Li+ for Zn2+ leads to decrease the effective positive charge of (0001) surface and as a result to decrease the growth rates in the presence of Li-ion in the starting solution.