Room-temperature rf-magnetron sputter-deposited W-doped indium oxide: decoupling the influence of W dopant and O vacancies on the film properties

Tungsten-doped indium oxide (IWO) thin films were deposited at room temperature using rf-magnetron sputtering. The optical, electrical, and structural properties of the IWO films were studied as functions of the O2-dilution fraction in the Ar sputtering gas. The W-doping level, and contributions of intrinsic oxygen vacancies and W dopant to the free carrier concentration were studied. Windows of optimum deposition conditions are demonstrated where amorphous and smooth-surfaced IWO films are obtained with low resistivity of 3.5 × 10−4 Ω cm, high mobility of 45 cm2 v−1 s−1, and high optical transparency (visible and NIR transparencies of 83 and 80 %, respectively). The observed optoelectronic properties are discussed in light of the underlying electron transport mechanisms.