Surface composition and electronic properties of indium tin oxide and oxynitride films

The surface properties of indium tin oxynitride films prepared by rf-sputtering in nitrogen atmosphere were investigated by X-ray and ultraviolet photoelectron spectroscopy as well as electron energy loss spectroscopy and Auger electron spectroscopy depth profiling. The results are compared to reference measurements on conventional rf-sputtered indium tin oxide films. The incorporated nitrogen is present in different chemical environments. Employing these different spectroscopic techniques, it was found that desorption of nitrogen from the ITON structure upon annealing is the origin of the observed drastical changes in the surface composition and electronic structure. The formation of oxygen vacancies and Sn surface segregation upon annealing is linked to improvements in the physical properties (larger spectral range of transmittance and higher conductivity) of the films.