Hydrothermal epitaxy of ZnO:Co diluted magnetic semiconducting single crystalline films

ZnO:Co films with room-temperature ferromagnetism have been hydrothermally grown in water at 90 S C using a ZnO seed layer on MgAl2O4 (111) substrates. High-resolution x-ray diffraction shows an epitaxial ZnO:Co single crystalline film with an out-of-plane orientation of ZnO:Co < 001 >parallel to MgAl2O4 < 111 > and an in-plane orientation of ZnO:Co[110]parallel to MgAl2O4[-1-12] and ZnO:Co[-110]parallel to MgAl2O4[-110]. A saturation magnetization of 0.83 emu/cm(3) and a coercivity of 40 Oe were obtained for the epitaxial Zn0.98Co0.02O film at room temperature. Hydrogen unintentionally incorporated in the hydrothermal synthesis is suggested to contribute to the ferromagnetic properties in the diluted magnetic semiconductor by enhancing carrier concentration as a shallow donor. (C) 2008 American Institute of Physics.