Influence of an In2O3 buffer layer on the properties of ITO thin films

In the present study, an indium oxide (In2O3) thin film was deposited as a buffer layer between ITO (indium tin oxide) and PES (polyestersulfone) by RF (radio frequency) magnetron sputtering at room temperature, and X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were conducted to characterise the structural variation. The random texture of the ITO/In2O3 multilayered film favoured the (2 2 2) crystallographic plane rather than the (4 0 0) plane, which was favoured in single-layer ITO films. Transmission electron microscopy (TEM) observations further indicated that the buffer layer of In2O3 film was amorphous, while the ITO film was characterised by a columnar structure that was oriented perpendicular to the substrate surface. The electrical and optical properties of ITO/In2O3 multilayered films were enhanced due to the superior crystallinity and larger grain size of the material, as observed by XRD and FESEM. The multilayered film presented an electrical resistivity of 3.1 × 10−4 Ω cm, which is significantly better than that of a single-layer ITO film without an In2O3 buffer layer (4.7 × 10−4 Ω cm). In addition, optical transmission through the multilayered film increased by 2–4% due to the widening of the band gap by 0.2 eV, which was attributed to a Burstin–Moss shift.