Reductive Corrosion Behavior of ITO in a Phosphoric Solution

Abstract

The reductive corrosion behavior of ITO, which can occur when ITO and Al are coupled, has been investigated electrochemically in phosphoric acid solutions. ITO was reduced to metallic In and Sn both when coupled with Al and when polarized to below －0.7 V vs. SCE potentiostatically. The reductive degradation of ITO was successively suppressed by the addition of nitric acid into the phosphoric acid solution because of the preferential reduction of nitrate ions. Although ITO cannot be dissolved anodically in a phosphoric acid solution, the reduced component can be dissolved anodically. Thus, the desired amount of ITO can be removed electrochemically in a phosphoric acid solution.