Preparation of Nitrogen Doped ZnO Dilute Ferromagnetic Semiconductor by Magnetron Sputtering

Abstract

ZnO/Zn3N2 multilayer films were synthesized on slide glass substrates by radio-frequency (RF) magnetron sputtering technology with RF powers of 100 W. After annealing in oxygen atmosphere for 3 hours at the temperature changed from 473 K to 873 K, the multilayer films were changed to be single-layer films of nitrogen doped ZnO dilute ferromagnetic semiconductor. The structural, elementary constituents, carrier concentration and magnetic properties of the films were investigated with X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), hall-effect measurements and vibrating sample magnetometer (VSM) magnetization measurements, respectively. The XRD measurements revealed that the nitrogen doped ZnO films had a wurtzite structure with their crystal (002) directions oriented along the c-axis of the substrate. Hall-effect measurements indicated that nitrogen doped ZnO thin film, annealed at 673 K for 3 hour, had the best p-type properties. Carrier concentration and resistivity of the film was 3.12 × 1017 cm-3 and 93 Ωcm, respectively. A Lakeshore 7407 vibrating sample magnetometer was employed for magnetization (M) versus applied field strength (H) investigations of these thin films. A typical hysteresis loop was found in the observed M–H curve of the samples, demonstrated that the films annealed at 673 K for 3 hour were ferromagnetic at 300 K. The XPS analysis revealed the presence of Zn-N chemical bonding in the films. It suggested that nitrogen atoms are substituted at the oxygen sites of the ZnO films and mediate the ferromagnetic properties of the films.