Structure, optical, and magnetic properties of sputtered manganese and nitrogen-codoped ZnO films

Abstract

To realize the hole-mediated ferromagnetism, manganese and nitrogen-codoped ZnO (Zn1−xMnxO:N) films were prepared on sapphire (0001) by reactive radio-frequency (rf) magnetron sputtering from Zn0.97Mn0.03O ceramic targets using N2 gas. X-ray photon spectra reveal that the doped Mn ions are mainly in divalent states and the coexistence of O–Zn and N–Zn bonds in the films. According to the absorption spectra, the band gap of Zn0.97Mn0.03O:N films is about 3.15eV, which is slightly lower than that of ZnO films (3.20eV). Compared with Zn0.97Mn0.03O films, ferromagnetic behavior of Zn0.97Mn0.03O:N films were significantly changed with a coercivity of about 70Oe, a saturation magnetization of 0.92μB∕Mn2+ and a remanance over 0.15μB∕Mn2+ at 300K, while at 10K, they increased to be about 110Oe, 1.05μB∕Mn2+ and 0.23μB∕Mn2+, respectively. However, rapid thermal annealing treatment in pure oxygen results in a significant decrease on the magnetic properties of the films.