Al/ZnO/SiO2/Si structure is experimentally studied for application to SAW devices and other progressive devices. The good agreement between the experimental and theoretical value of Cac/Cinv shows that the high density interface states do not exist at the SiO2-Si interface of the Al/ZnO/SiO2/Si (MZOS) structure. It is found that hysteresis characteristics of the MZOS–C versus the gate bias depends on the voltage sweep rate and the resistivity of ZnO film. It is confirmed that the quasi-stable flat band voltage of the MZOS-C depends on the ZnO thickness and sputtering rf power.