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

摘要

To realize the hole-mediated ferromagnetism, manganese and nitrogen-codoped ZnO (Zn_(1-x)Mn_xO: N) films were prepared on sapphire (0001) by reactive radio-frequency (rf) magnetron sputtering from Zn_(0.97)Mn_(0.03)O ceramic targets using N_2 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 Zn_(0.97)Mn_(0.03)O: N films is about 3.15 eV, which is slightly lower than that of ZnO films (3.20 eV). Compared with Zn_(0.97)Mn_(0.03)O films, ferromagnetic behavior of Zn_(0.97)Mn_(0.03)O: N films were significantly changed with a coercivity of about 70 Oe, a saturation magnetization of 0.92 μ_B/Mn~(2+) and a remanance over 0.15 μ_B/Mn~(2+) at 300 K, while at 10 K, they increased to be about 110 Oe, 1.05 μ_B/Mn~(2+) and 0.23 μ_B/Mn~(2+), respectively. However, rapid thermal annealing treatment in pure oxygen results in a significant decrease on the magnetic properties of the films.