The properties of reactively-sputtered, stoichiometry-controlled and optimum-conductivity transparent indium oxide films as a function of their titanium, aluminium and zinc content; comparisons with the use of tin as a dopant

Indium films doped with controlled amounts of original dopants of aluminium, titanium and zinc have been made with their stoichiometry controlled to give optimum electrical and optical properties. This was made possible fay a technique where they were deposited by the successive sputtering of a thin metal film followed by the anodisation of it, using the plasma created by an unbalanced magnetron. The processes involved transportation between stages with medium-frequency (40 kHz) power used to suppress any arcing at the target, when it was operated in a high concentration of oxygen in the atmosphere. These simply controlled processes gave high rate deposition of doped indium oxide films with resistivities of around 4 μΩ m and a film/glass substrate transmittance of around 80%. In particular it was found that doping with titanium was more successful than with tin, giving less blue absorption and a wider process window in the pressure of oxygen used with the process.