Structural and electrochemical properties of ZrO2 center dot H-x thin films deposited by reactive sputtering in hydrogen atmosphere as solid electrolytes

Abstract

The feasibility of applying ZrO2 center dot Hx thin films is solid electrolytes in solid-state ionic energy systems, such as solid oxide fuel cells and supercapacitors was studied. ZrO2 center dot H-x thin films were deposited on Pt/Ti/SiO2/Si substrates by radio-frequency reactive sputtering with various hydrogen volume fractions in reactive gas. With a variation in hydrogen volume fraction, the surface roughness of the as-deposited films increased. In addition, the structure of the as-deposited films grew in the [I I I] direction with an increase in hydrogen volume fraction. By Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) studies, the Zr/O ratio and hydrogen distribution were evaluated. On the basis of a sample structure of Pt/ZrO2 center dot H-x/Pt/Ti/SiO2/Si for measuring an electrochemical property, an impedance measurement conducted at room temperature revealed an ionic conductivity of 1.67 x 10(-6) S/CM, suggesting that ZrO2 center dot H-x thin films can possibly be used as solid oxide thin film electrolytes in all solid-state ionics power devices requiring a hydrogen conducting electrolyte.