Comparative studies on Zn0.95Co0.05O thin films on C- and R-sapphire substrates

Zn_0.95Co_0.05O precipitate-free single crystalthin films were synthesized by a dual beam pulsed laser depositionmethod. The films form a wurtzite structure whose hexagonal axis isperpendicular or parallel to the plane of the surface depending onthe C-plane (0001) or R-plane (11bar 20) sapphire substrate. Basedon the results of high-resolution transmission electron microscopyand x-ray diffraction, C-plane films show larger lattice mismatch.The films exhibit magnetic and semiconductor properties at roomtemperature. The coercivity of the film is about 8000 A/m at roomtemperature. They are soft magnetic materials with small remanentsquareness S for both crystal orientations. There is no evidence toshow that the anisotropy is fixed to the hexagonal axis (C-axis) forthe wurtzite structure.