Synthesis and characterisation of nitrogen-doped ZnO thin films

Nitrogen doped ZnO thin films were prepared using a DC-Magnetron sputtering technique. The samples were investigated using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). XPS revealed the presence of nitrogen in the films prepared under high oxygen to nitrogen ratio N/O ≥ 5/1. One N 1s peak located at 397 eV binding energy (BE) was assigned to atomic nitrogen. The other located at a BE of 399 eV was assigned to N due to formation of oxynitride. The XRD spectrum of the samples prepared under N/O ratio ≥ 1/5 showed a single peak at 2θ ∼ 33.60 assigned to ZnO (002) plane indicating a strong texture along the c-axis. Both peaks were shifted toward lower angles, as compared to pure ZnO film, indicating an expansion of the unit cell as a result of the insertion of nitrogen in the lattice. The nanostructure of the films was investigated by atomic force microscopy.