Comparison of the electrical and optical properties of direct current and radio frequency sputtered amorphous indium gallium zinc oxide films

► Amorphous InGaZnO4 (a-IGZO) films were prepared with different sputtering modes. ► Electrical and optical properties of the different films were compared. ► Fermi level (△EF) shift in a-IGZO films were tested by X-ray photoelectron spectroscopy. ► The relation of △EF with the properties of a-IGZO films were discussed. ► Work function was tested by ultraviolet photoelectron spectroscopy.