Electrochromic properties of nickel oxide films prepared by introduction of hydrogen into sputtering atmosphere

Colorless as-deposited films of nickel oxide were prepared by introduction of hydrogen into sputtering atmosphere, which is mixture of argon and oxygen. The electrochromic characteristics of the films thus obtained were investigated. Change in optical density depended linearly on the density of injected charges. The coloration efficiency decreased with increasing RF power of sputtering. On the other hand, the coloration efficiency increased a little with increasing hydrogen content in sputtering atmosphere up to 40%, but decreased steeply at 50%. The maximum coloration efficiency of 36 cm(2)/C was obtained at 8 Pa total pressure with hydrogen content of 40%.