Annealing of indium tin oxide films by electric current: properties and structure evolution

As a new method of indium tin oxide (ITO) annealing in vacuum, direct electric current flow through the film is proposed. ITO films of about 170 nm thickness were produced by reactive pulsed magnetron sputtering. During annealing at constant electric power, the film resistance, free electron density and structure evolution were monitored in situ. Compared to conventional isothermal annealing, the current annealing is more efficient with a noticeable reduction of the thermal budget and a decrease of the kinetic exponent of the crystallization. Electrical inhomogeneities of the film, which produce locally overheated regions, are discussed as potential reason for the acceleration of the crystallization process.