Electrical and mechanical properties of indium‐tin‐oxide films deposited on polymer substrate using organic buffer layer

Abstract

The electrical and mechanical properties in indium‐tin‐oxide films deposited on polymer substrate were examined. The materials of substrates were polyethersulfone (PES) which have gas barrier layer and anti‐glare coating for plastic‐based devices. The experiments were performed by rf‐magnetron sputtering using a special instrument and buffer layers. Therefore, we obtained a very flat polymer substrate deposited ITO film and investigated the effects of buffer layers, and the instrument. Moreover, the influences of an oxygen partial pressure and post‐deposition annealing in ITO films deposited on polymer substrates were clarified. X‐ray diffraction observation, measurement of electrical property, and optical microscope observation were performed for the investigation of micro‐structure and electro‐mechanical properties, and they indicated that as‐deposited ITO thin films are amorphous and become quasi‐crystalline after adjusting oxygen partial pressure and thermal annealing above 180 °C. As a result, we obtained 20–25 O/sq of ITO films with good transmittance (above 80 %) ofoxygen contents with under 0.2 % and vacuum annealing. Furthermore, using organic buffer layer, we obtained ITO films which have a rather high electrical resistance (40–45 O/sq) but have improved optical (more than 85 %) and mechanical characteristics compared to the counterparts. Consequently, a prototype reflective color plastic film LCD was fabricated using the PES polymer substrates to confirm whether the ITO films could be realized in accordance with our experimental results.