Combined effects of oxygen pressures and RF powers on the electrical characteristics of ITO-based multilayer transparent electrodes

The opto-electrical properties of plasma-treated ITO films were investigated as functions of oxygen pressures (3.33 and 26.66 Pa) and radio-frequency (RF) plasma powers (50 and 150 W). The plasma-treated samples showed higher transmittance than the untreated sample. After the low-oxygen treatment, the carrier concentration increased with increasing plasma RF power and the figure of merit (FOM) also increased from 1.17 × 10⁻³ to 1.65 × 10⁻³ Ω⁻¹. This was not the case for the high-oxygen treatment. The ITO surfaces became smoother with increasing RF power. It was shown that unlike the high-oxygen treated samples, the In 3d and Sn 3d core levels for the low-oxygen-treated ITO films were shifted to higher energies compared to that of the untreated sample. ITO films of ITO/Ag/ITO multilayers (IAI) were plasma-treated at different conditions. Their transmittance maxima were in the range of 91.58–92.32% at 492–501 nm. The bottom-ITO-treated sample gave 23.1% higher mobility and 19% lower sheet resistance than the untreated IAI. The wetting characteristics of deionized (DI) water on the ITO films showed that the surface energy of ITO films increased from 34.22 to 71.14 mJ/m² when the oxygen pressures increased from 0 to 26.66 Pa.