Band gap engineering of indium zinc oxide by nitrogen incorporation

• IZON thin films were deposited by RF reactive sputtering at room temperature.
• The effects of nitrogen on physical properties of IZO were analyzed.
• Optical properties of IZON were studied by SE and UV–vis spectroscopy.
• Adachi and classical parameters were quantitative and qualitatively congruent.
• Nitrogen induces a gradual narrowing band gap from 3.5 to 2.5 eV on IZON films.

The effects of nitrogen incorporation in indium zinc oxide films, as grown by RF reactive magnetron sputtering, on the structural, electrical and optical properties were studied. It was determined that the variation of the N2/Ar ratio, in the reactive gas flux, was directly proportional to the nitrogen percentage measured in the sample, and the incorporated nitrogen, which substituted oxygen in the films induces changes in the band gap of the films. This phenomenon was observed by measurement of absorption and transmission spectroscopy in conjunction with spectral ellipsometry. To fit the ellipsometry spectra, the classical and Adachi dispersion models were used. The obtained optical parameters presented notable changes related to the increment of the nitrogen in the film. The band gap narrowed from 3.5 to 2.5 eV as the N2/Ar ratio was increased. The lowest resistivity obtained for these films was 3.8 × 10−4 Ω cm with a carrier concentration of 5.1 × 1020 cm−3.