Effect of nitrogen incorporation on the structural, optical and dielectric properties of reactive sputter grown ITO films

The changes in the optical, microstructural and electrical properties, following the nitrogen incorporation into indium tin oxide thin films are investigated. The films are formed by r.f. sputtering from an indium-tin-oxide (80% In2O3-20% SnO2) target in a mixture of Ar and N2 plasma (75% N2-25% Ar and 100% N2 respectively) on fused silica glass substrate. The impact of rapid thermal annealing (up to 500 °C, in N2 ambient) on the properties of indium tin oxynitride (ITON) thin films is also reported. The UV-vis-NIR ellipsometry (SE) characterization of ITON films was performed assuming several realistic approaches based on various oscillator models, using a chemical composition gradient depth profiling, in agreement with the X-ray photoelectron spectroscopy measurements. The Hall measurements show that the ITON films prepared by r.f. sputtering in 75% N2 and annealed at 500 °C behave as degenerate semiconductors. X-ray diffraction analysis proved that ITON thin films retain an amorphous structure even after RTA at 500 °C in N2 ambient and atomic force microscopy showed the formation of continuous and smooth ITON thin films, with a morphology consisting in quasispherical nanometric particles.