Enhanced adhesion between polycarbonate substrates and tin-doped indium oxide films by ion-assisted reaction

Abstract

Adhesion between polycarbonate (PC) substrates and tin-doped indium oxide (ITO) films was improved by an ion-assisted reaction (IAR) process in which the PC surfaces were irradiated by 1 keV Ar + ions in oxygen gas environment. The dose of Ar + ions was changed from 5×10 14 to 5×10 16 ions/cm 2 and the oxygen gas with a flow rate of 4 sccm (ml/min) was introduced near the PC surfaces during Ar + ion irradiation. After IAR treatment, the contact angles of the PC surfaces to water were changed from 78° to 12° and those to formamide from 63° to 5°. X-ray photoelectron spectroscopy analysis showed that hydrophilic groups were formed on the modified PC surfaces by a chemical reaction between the unstable chains induced by the ion irradiation and the oxygen gas, and the newly formed hydrophilic group was identified as –(CO)– bond (carbonyl group). The surface energy of the modified PC surfaces increased mainly due to the polar component related to the hydrophilic group. Based on these results, a mechanism of adhesion improvement for the ITO /PC system was proposed.