Real-time evolution of the ITO film properties and structure during annealing in vacuum

Indium tin oxide films produced by reactive middle frequency dual magnetron sputtering were annealed in vacuum at a constant rate of the temperature enhancement. The film electrical and optical properties have been studied in situ along with direct characterization of the structure. Even in amorphous state the film resistivity significantly decreases at increasing temperature due to a free electron density enhancement likely by oxygen vacancies creation. The rapid crystallization within the temperature range 250-280 °C leads to further decrease of the resistivity due to a Sn donor activation. The resistivity and optical properties depend non-linearly on the crystalline fraction.