The degradation of fluorine doped tin oxide films in a hydrogen plasma

Abstract

The effect of hydrogen plasma on the properties of transparent conducting fluorine doped tin oxide films has been studied. Exposure to hydrogen plasma results in the reduction of the film surface to elemental tin and suboxides of tin. The thickness of the reduced layer increases with increasing exposure to plasma and finally saturates to a thickness of 100 to 150 nm, having an extremely rough texture. The presence of the rough metal-rich surface layer decreases the visible transmittance drastically due to increased reflectance and absorptance of the films. The sheet resistance of the films increases due to the formation of suboxide. Annealing of the plasma exposed film in oxygen results in a recovery of the transparency except when the film surface is severely damaged and remains extremely rough after the annealing treatment.