Microstructural characterization of high-quality indium tin oxide films deposited by thermionically enhanced magnetron sputtering at low temperature

Abstract

In this work, high-quality indium tin oxide (ITO) films are deposited by thermionically enhanced magnetron sputtering at a low deposition temperature. Microstructural evolution in the various growth stages is elucidated using material characterization techniques including grazing-incidence X-ray diffractometry and high-resolution transmission electron microscopy.Experimental results reveal that the ITO film is mainly amorphous throughout its thickness when it is deposited at ambient temperature without thermionic enhancement (TE). In contrast, the ITO film that is deposited at ambient temperature with TE has a columnar crystalline structure with grains of 40–80 nm in size. When the deposition temperature is increased to 200 °C with TE, the film exhibits a complete columnar crystalline structure throughout its thickness with grain sizes of 60–100 nm. The sputter-deposited ITO films using TE exhibit a higher average visible transmittance and a lower electrical resistivity than those without using TE because of the enhancement in their crystalline growth by the intensive ion bombardment.