Characterization of Indium Tin Oxide Films after Annealing in Vacuum

ITO thin films were deposited on glass substrate by dc magnetron sputtering without substrate heating. The effects of annealing in vacuum on the structural, optical and electrical properties were investigated. The samples of 120 nm ITO films were separately annealed at 200, 250, 300 and 350°C for 1 hour. The results showed that the increasing of the annealing temperatures improve the crystallinity of the films, increase the grain sizes and improve their optical and electrical properties. The optical transmission of films in the visible region increase while in the near infrared region decrease with increasing the annealing temperatures. The relative intensities I(400)/I(222) of ITO films increase but the resistivity decrease with increasing the annealing temperature. The prepared ITO film as-deposited has a resistivity of 2.47×10-3 Ω.cm and decreases to 3.95×10-4 Ω.cm after annealing at 350°C for 1 hour and energy gap increases from 3.99 eV to 4.10 eV.