Ion beam pretreatment of polymeric substrates for ITO thin film deposition

Polycarbonate (PC) surfaces were pretreated by an 1 keV Ar+ ion irradiation in oxygen environment to improve surface properties before depositing indium tin oxide (ITO) films. The hydrophobic PC surfaces were converted into more hydrophilic ones after a surface modification. Improved wettability of the treated PC surfaces was due to the formation of new polar groups on the surfaces, responsible for the increase of polar component in the surface energy. Chemical interaction between unstable chains induced by energetic ion bombardment and oxygen gas resulted in the formation of the polar groups, which were identified as oxygen containing carbon bonds such as carbonyl by the XPS study. In the initial growth stage of the ITO films on the PC substrates, the newly formed polar groups prevented hill-locks from growing on the surfaces, which contributed to the improvement of thermal stability in the ITO thin films on the modified PC substrates. The Ar+ ion irradiation in oxygen environment also led to a significant adhesion enhancement of PC substrates to ITO films which was explained in terms of the physical and chemical changes on the PC surfaces.

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