Depth distribution of cations electrochemically-inserted into WO₃ thin films

Abstract

Li⁺ and H⁺ ions were electrochemically inserted into amorphous WO₃ films prepared by an R.F. magnetron sputtering method. The depth distribution of the inserted cations was investigated according to the refractive index profiles obtained by a prism coupler method. After cation insertions, the decrease in refractive indices was commonly observed in the WO₃ films adjacent to the ITO electrodes. After further insertions, however, the changes in the refractive index profiles were different in the cases between Li⁺ and H⁺. The relation between depth distribution of cations and coloration was also discussed.