Effects of Tin Concentrations on Structural Characteristics and Electrooptical Properties of Tin-Doped Indium Oxide Films Prepared by RF Magnetron Sputtering

Structural characteristics and electrooptical properties of Sn-doped In2O3(ITO) films were investigated in terms of Sn concentrations from 5.34 to 8.99 (Sn/In at.%) with changing oxygen partial pressure and substrate temperature during deposition, in spite of using an ITO target with the same Sn concentration ( 7.50 SnO2wt%, 7.17 Sn/In at.%). The resistivity of the films deposited at 200 and 300° C had a clear tendency to decrease with decrease of the total Sn content. Sn atoms incorporated in the ITO films were classified into two types, i.e., electrically active substitutional Sn atoms contributing to carrier density and electrically nonactive impurities forming nonreducible tin-oxide complexes, which were revealed by precise lattice constant measurement. The change in the Sn concentration was found to be associated with the preferred orientation of the crystal grains, which was dominated by the deposition conditions and should reflect the crystal growth processes.