STUDY OF THE STRUCTURAL-PROPERTIES OF ZNO THIN-FILMS BY X-RAY PHOTOELECTRON-SPECTROSCOPY

X-ray photoelectron spectroscopy (XPS) analysis was performed on ZnO films prepared on glass substrates by DC reactive magnetron sputtering at different substrate temperatures (room temperature to 450-degrees-C). In the 0 ls spectra two resolved peaks were observed. The lower energy peak, located at 530 eV, corresponds to O-Zn bonding, while the higher energy peak, located at 532 eV, could be assigned to OH(531.5 eV) and/or H2O(533 eV) species. As the substrate temperature is increased, the oxygen component located at higher energy decreases. This variation was correlated with the structural properties of the films. The films prepared by DC reactive magnetron sputtering generally have a columnar structure with many pores. In air some of these pores are filled with water and result in the appearance of a higher energy peak in the 0 ls spectra. The decrease of the oxygen component located at higher energy indicates the decrease of the porosity of the films. The results obtained by scanning electron microscopy measurements were in agreement with this conclusion.