Improvement of structural and optoelectrical properties by post-deposition electron beam annealing of ITO thin films

Sn-doped In2O3 (ITO) thin films were deposited on a glass substrate with reactive RF magnetron sputtering and then post-deposition electro-annealed. The electron accelerating voltage was varied from 300 to 900 V, and the substrate temperature was increased to 250 °C with an electron accelerating voltage of 900 V for 20 min in a 4 × 10−1 Pa vacuum. As-deposited and ITO films electro-annealed at low energy (≤600 eV) were found to be in the amorphous phase, while ITO films electro-annealed at 900 eV showed diffraction peaks of the ITO (222) and (400) planes. As the electron accelerating voltage increased, the electrical resistivity decreased to as low as 6 × 10−4 Ωcm, and the mean optical transmittance also increased from 79 to 82% in the visible wavelengths. The electro-annealed films showed a higher figure of merit (1.8 × 10−3 Ω−1) than the as-deposited ITO films (6.7 × 10−3 Ω−1), indicating that electro-annealed ITO films have better optoelectrical performance than as-deposited films.