Magnetic Properties of Zn$_{1 - {rm x}} {hbox {Co}}_{rm x}$O Thin Films Grown by RF Magnetron Co-Sputtering in Ar and N$_{2}$O Atmosphere

摘要

The Zn$_{1 - {rm x}} {hbox {Co}}_{rm x}$O and Zn $_{1 - {rm x}}$Co $_{rm x}$N $_{rm y}$O $_{1 -{rm y}}$ thin films were grown by RF magnetron co-sputtering, but in different sputtering gases (Ar and N$_{2}$O, 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 Co$^{2 +}$ ions substituted tetrahedrally coordinated Zn$^{2 +}$ 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 Zn$_{1 - {rm x}} {hbox {Co}}_{rm x}$O had $n$-type conduction with electron concentration of 10$^{19}$ cm$^{- 3}$, and exhibited paramagnetism. Due to the charge compensation by N doping, the Zn$_{1 - {rm x}}$Co$_{rm x}$N$_{rm y}$O$_{1 -{rm y}}$ possessed large resistivity, and also presented paramagnetism, besides the film Zn$_{1 - {rm x}}$Co$_{rm x}$N$_{rm y}$O$_{1 -{rm y}}$ $({rm x} = 0.0162, {rm y} = 0.0004)$ , which possessed room temperature ferromagnetism (RTFM).