Magnetic Properties of Zn1-xCoxO Thin Films Grown by RF Magnetron Co-Sputtering in Ar and N2O Atmosphere

The Zn1-xCoxO and Zn1-xCoxNyO1-y thin films were grown by RF magnetron co-sputtering, but in different sputtering gases (Ar and N2O, respectively). X-ray diffraction analysis indicated that all the samples had c-axis preferred orientation, without any segregated secondary phase. UV-visible spectroscopy and X-ray photoelectron spectroscopy showed that Co2+ ions substituted tetrahedrally co-ordinated Zn2+ ions site for the films. The electrical and magnetic properties were investigated by the Hall effect and superconducting quantum interference device (SQUID) measurements, respectively. The Zn1-xCoxO had n-type conduction with electron concentration of 10(19) cm(-3), and exhibited paramagnetism. Due to the charge compensation by N doping, the Zn1-xCoxNyO1-y possessed large resistivity, and also presented paramagnetism, besides the film Zn1-xCoxNyO1-y (x = 0.0162, y = 0.0004), which possessed room temperature ferromagnetism (RTFM).