Electronic State of Amorphous Indium Gallium Zinc Oxide Films Deposited by DC Magnetron Sputtering with Water Vapor Introduction

Amorphous indium gallium zinc oxide (a-IGZO) films were fabricated using dc magnetron sputtering with water vapor (H 2 O or D 2 O) introduction. To determine the incorporation pattern of water, films were characterized by secondary ion mass, Fourier transform infrared, Raman, and hard X-ray photoelectron spectroscopies. Chemically bound hydroxyl groups were observed, and more hydroxyl bonds existed nearer to the interface between the substrate and film than in the film. Furthermore, for a-IGZO films, subgap densities of states near valence band maxima increased with the H 2 O partial pressure during deposition, which can be attributed to defect-level generations due to H and O.