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The photoluminescence and magnetism of nitrogen-implanted ZnO

Single crystal ZnO was implanted using nitrogen ions with an energy of 60 keV. The microstructure, photoluminescence (PL) and magnetism were studied in detail. Except for nitrogen, no other impurity can be detected by x-ray photoelectron spectra measurements. The room temperature PL of pure ZnO consists of a weak ultraviolet (UV) emission band and a strong green emission band. The PL and electrical conductivity can be suppressed by nitrogen implantation or by annealing in air. However, the two emission bands of pure ZnO can be enhanced intensively by Ar+ etching. The PL is related to the structure defects. Moreover, the intensity of UV luminescence is likely correlated to the electrical conductivity. Ferromagnetism cannot be obtained in the nitrogen-implanted sample from 77 to 300 K. The absence of ferromagnetism in nitrogen-implanted ZnO may be because there is no strong interaction between N 2p and O 2p electrons as nitrogen is a deep acceptor in ZnO.