The Electronic Properties of ITO Film Prepared on Plastic Substrates

The electronic properties of ITO (Indium Tin oxide) films prepared on PET (polyethylene terephtalate) substrates were investigated. ITO films were deposited with DC magnetron sputtering method using In-Sn alloy target under the condition that the minimum resistivity could be obtained with Ar and O2 gas mixture. Organic compounds such as acetaldehyde and ethylene glycol were found to be released from PET upon heating. SIMS measurements revealed that the amount of gas released from the PET substrate is parallel to that of residual carbon in ITO films deposited on the PET substrate. This result implies the desorbed gases were incorporated into the ITO film during the deposition. When ITO film with larger carbon content was heated at 130°C for 5 hours, the carbon concentration was decreased to 1/10 of initial. Hall measurements showed that the increase in resistivity after heat treatment was due to the decrease in the carrier density.