Effect of the oxidation temperature on microstructure and conductivity of Zn x N y thin films and their conversion into p-type ZnO:N films

Transparent p-type ZnO:N thin films have been fabricated by the oxidation of n-type Zn x N y films. The Zn x N y thin films on glass substrate were deposited by pulsed filtered cathodic vacuum arc deposition using metallic zinc (99.999%) as a cathode target in pure nitrogen plasma. The properties of the films were examined after oxidation between 350 and 550 °C in air atmosphere. The atomic force microscopy (AFM) analysis revealed that the surface morphology was smooth. As-deposited Zn x N y films were opaque and conductive (? = 4.36 × 10 -3 ? cm, N D = 7.70 × 10 21 cm 2 /Vs) due to excess of Zn in the structure. After oxidation between 350 and 500 °C, p-type ZnO:N thin films were obtained. The lowest resistivity of 44.50 ? cm with a hole concentration and Hall mobility of 2.08 × 10 17 cm -3 and 0.673 cm 2 /Vs, respectively, was obtained after oxidation at 450 °C. However, when the oxidation temperature reached to 550 °C, the conduction type of the ZnO:N film was changed from p-type to n-type. X-ray photoemission spectroscopy (XPS) analysis confirmed the formation of ZnN bonds and substitution incorporation of oxygen for nitrogen on the surface of the film. Besides, with a further increase of oxidation temperature to 550 °C, the decrease of N concentration in the sample was also confirmed by XPS analysis. © 2013 Elsevier B.V.106T613This work was supported by the Research Foundation of Cukurova University and the Scientific and Technological Research Council of Turkey (Grant No: 106T613 ). The Authors thank to H. Karaagac from Middle East Technical University for XRD measurements and Florian Klappenberger, Katharina Diller, Johannes V. Barth fromTechnische Universitat München for XPS measurements