Chemistry and kinetics of ZnO growth from alkaline hydrothermal solutions

Special features (polar growth and nonstoichiometry) of ZnO single crystals grown on seed plates of various crystallographic orientations in the ZnO-KOH-H2O and ZnO-KOH-LiOH-H2O hydrothermal systems are analyzed. The growth proceeds via the interaction of ZnO22- anions with crystal surfaces, and its rate depends on the atomic structure and electric charge of the surface. The mechanism underlying the influence of Li+ ions on polar ZnO growth is considered. Partial replacement of Zn2+ by Li+ decreases the positive charge the (0001) face and hinders the attachment of ZnO22- anions. The incorporation of Li ions into the (000 (1) over bar) face decreases its negative charge and accelerates growth in the [ 000 (1) over bar] direction.