Properties of Indium–Zinc-Oxide Films Synthesized by Radio Frequency Magnetron Sputtering Based on Gas Phase Monitoring Using Multi-Micro Hollow Cathode Lamp

Indium–zinc-oxide (IZO) films were synthesized by radio frequency magnetron sputtering. In order to clarify the mechanisms of IZO film formation, the absolute densities of In and Zn atoms were measured simultaneously by absorption spectroscopy employing the multi-micro hollow cathode lamp. Their densities were measured to be 109 to 1011 cm-3 and increased with pressure from 1 to 10 Pa. The density ratios of In to Zn in the gas phase corresponded to the ratios of film composition, and the relative amount of Zn atom increased with decreasing pressure. Carrier density increased with decreasing density ratio of In to Zn owing to the increase in the number of oxygen vacancies, which was clarified from the O 1s spectra obtained by X-ray photoelectron spectroscopy. A low resistivity of 10-6 Ω m and an optical transmission of over 80% in the visible region were achieved at a pressure of 1 Pa.