Tin-doped indium oxide (ITO) films fabricated on glass substrates using a hot-cathode plasma sputtering method exhibited low resistivity of 9.7×10 −5 Ωcm, which is due to a high carrier density of 2.1×10 21 cm −3 . The change in the number of carriers, N, as a function of film thickness d, strongly suggests that oxygen extraction in the initial stages of ITO film growth on the glass substrate surface, creates oxygen vacancies as an electron carrier source for improvement in the resistivity of the films.