Transparent conducting oxides of metals and alloys made by reactive magnetron sputtering from elemental targets

Abstract

Oxide films were made in a continuous process onto plastic sheet would from reel to reel over a drum exposed to the sputtering material and residual active gas. Single and double coaxial magnetron sources were used to create conducting elemental oxides of indium, cadmium, tin and zinc and alloy oxides of a combination of these materials. Optimum stoichiometric composition of oxygen was determined for each material using continuous monitoring of electrical conductivity and visual transparency. The composition of the films was determined with XPS, AES and electron microprobe analysis. The films were assessed for electrical conductivity, visual transparency and the Hall effect parameters of carrier density and mobility. Indium and cadmium oxides proved the most conducting and stable with resistivities of 4.10 −6Ωm being obtainable with good visual transparency. The addition of a small quantity of tin to cadmium oxide had the effect of considerably changing the blue transmittance, removing the yellow appearance from the film. For the less conducting oxides of tin and zinc film resistivities of approximately 2.10 −4Ωm were obtained.