Tailoring of Point Defects in Polycrystalline Indium Tin Oxide Films with Postirradiation of Electronegative Oxygen Ions

We have developed a state-of-the-art technology to tailor oxygen-related point defects such as oxygen vacancies (V-o) and structural defects of polycrystalline highly conductive Sn-doped In2O3 (ITO) films by a postirradiation of electronegative oxygen (O-) ions. The intentional oxygen doping that would annihilate V-o decreases carrier density (n(e)) from 9.3 X 10(20) to 7.1 X 10(20) cm(-3) with an increase of Hall mobility (mu(H)) from 44 to 51 cm(2).v(-1).s(-1), and subsequently, n(e) drastically decreases down to 1.2 X 10(19) cm(-3) together with a decrease in mu(H) owing to a formation of Sn-O neutral complexes with a further increase in the amount of oxygen atoms that should fill the structural defects while retaining their crystal structure. Upon the filling of the structural vacancies, the successful control of intrinsic point defects is probably caused by almost no difference in the ionic radii between In3+ having six-coordination and Sn4+ having eight-coordination. The O--ion-irradiation technology enables one to tailor the physical properties of ITO films over a wide range while retaining the crystal structure of the films.