Study on the chemical bond structure and chemical stability of N doped into TiO2 film by N ion beam implantation
Titanium dioxide (TiO2) film was deposited by DC pulse magnetron sputtering technique. The surface of TiO2 film was implanted by N ion beam at room temperature and N doped TiO2 (N TiO2) film was obtained. X ray diffractometer result showed that with the increase of sputtering power, the crystal structure of TiO2 film changed from amorphous to anatase polycrystalline structure. Transmission electron microscopy result revealed that nanoscale clusters existed in amorphous TiO2 film. The bandgap of TiO2 film was about 3.28 0.05 eV. X ray photoelectron spectroscopy results revealed that N ion was doped into TiO2 film as Ti N and Ti NO bonds. With increasing TiO2 film crystallinity, N atom percent and ratio of Ti N to Ti NO decreased and increased, respectively. TiO2 film deposited with 900 W in sputtering power, N atom percent decreased to 6.6 at. and ratio of Ti N to Ti NO increased to 0.81:1. The bandgap of N TiO2 film was about 3.02 0.07 eV. N atom percent and ratio of Ti N to Ti NO kept at 2.73 0.26 at. and (0.87 0.03):1 for all annealed N TiO2 films. The bandgap of annealed N TiO2 film was about 3.16 0.03 eV. So, the crystallinity of TiO2 film was one of most important parameters, which influenced the chemical bond structure and chemical stability of N in TiO2 films.