pH-Sensitive Gd2O3∕ SiO2Stacked Capacitors Prepared By Pure Water Anodic Oxidation

A high dielectric constant capacitor with stacked Gd2O3∕SiO2oxide prepared by anodic oxidation in pure water is reported in this study. The transmission electron microscopy results indicate that good uniform interfaces are observed. The relative dielectric constant of the anodic Gd2O3oxides is determined to have a value of about 12 by capacitance-voltage (C-V)measurement. High breakdown property and left-shift C-Vcurves are exhibited. This anodic oxidation Gd2O3∕SiO2stacked capacitor, which is used as a pH-sensitive element in the structure of an electrolyte insulator semiconductor (EIS), is investigated. A large shift of the flatband voltage is obtained when the double-layered (Gd2O3∕SiO2)EIS structures are immersed in various (pH2, 4, 6, 8, and 10) buffer solutions.