Low-Resistivity and High-Transmittance Indium Gallium Zinc Oxide Films Prepared by Co-Sputtering In2Ga2ZnO7 and In2O3 Targets

Abstract

Indium gallium zinc oxide (IGZO) films are deposited on glass substrates by co-sputtering In2Ga2ZnO7 and In2O3 targets. The structural, electrical, and optical properties of the IGZO films have been discussed as functions of substrate temperature and rf power supplied to the In2O3 target (Prf, In2O3). From x-ray diffraction patterns, a halo peak around 34° is observed, which is attributed to the amorphous-like ZnkIn2O3+k structure. The electrical resistivity decreases with increasing substrate temperature and Prf, In2O3. The optimum resistivity is 7.16 × 10 -4 Ω-cm obtained at 175 ° substrate temperature and 20 W Prf,In2O3. The optical characteristics indicate that IGZO films are direct-transition type semiconductors. The optical band gap energy widens with increasing In2O3 content in the IGZO films. The optical transmittance of films deposited with 10-W Prf, In2O3 is higher than 99% in the wavelength region from 516 to 535 nm.