Amorphous indium tungsten oxide films prepared by DC magnetron sputtering

Indium-tungsten-oxide (IWO) films were prepared by dc magnetron sputtering at ambient substrate temperature (Ts). Characteristics of the films were compared with those of In2O3–SnO2 (ITO) thin films prepared under the same condition. The sputter-deposited IWO films have entirely amorphous structure with an average transmittance of over 85% in the visible range and exhibit a minimum resistivity of 3.2 × 10−4Ωcm at W content [W/(In + W)] of 0.57 at.%. An in-situ heating X-ray diffraction measurement have shown that the crystallization temperature of IWO films is higher than those of ITO films (150–160∘C) and increases with increasing W content. This enabled a smooth amorphous surface of IWO films as compared with a rough surface of partially crystallized ITO films as revealed by an atomic force microscopy. IWO films are useful for transparent electrode of organic light emitting diode and polymer LCDs because of the low resistivity, high transparency and smooth surface obtainable by the conventional dc magnetron sputtering at room temperature.