Effective creation of oxygen vacancies as an electron carrier source in tin-doped indium oxide films by plasma sputtering

Abstract

We have investigated the effect of hydrogen on the resistivity, Hall mobility, and carrier density of ITO films on glass substrates using a low-pressure plasma sputtering method. It was found that a certain hydrogen content in the Ar plasma leads to improvement in the resistivity relating to an increase in the electron carrier density. The improvement is explained by oxide reduction due to the reaction of hydrogen radicals with indium oxide (In2O3). The effect of postannealing on the electrical properties confirmed that the improvement of the resistivity is a result of an increase in oxygen vacancies as the electron carrier source in the ITO film. Oxygen extraction in the initial stages of ITO film growth, due to the glass substrate surface, is suggested to create oxygen vacancies as the electron carrier source for improvement in the resistivity of the films.