A fabrication and magnetic properties study on Al doped Zn0.99Co0.01O dilution ferromagnetic semiconductors

This paper reports that a chemical method is employed to synthesize Co and Al co-doped ZnO, namely, Zn$_{0.99 - x}$Co$_{0.01}$Al$_{x}$O dilution semiconductors with the nominal composition of $x=0$, 0.005 and 0.02. Structural, magnetic and optical properties of the produced samples are studied. The results indicate that samples sintered in air under the temperatures of 500~\du\ show a single wurtzite ZnO structure and the ferromagnetism decreases with the increase of Al. Photoluminescence spectra of different Al-doped samples indicate that increasing Al concentration in Zn$_{0.99 - x}$Co$_{0.01}$Al$_{x}$O results in a decrease of Zn$_{\rm i}$, which resembles the trend of the ferromagnetic property of the corresponding samples. Therefore, it is deduced that the ferromagnetism observed in the studied samples originates from the interstitial defect of zinc (Zn$_{\rm i}$ ) in the lattice of Co-doped ZnO.