Bottom-contact organic thin film transistors with transparent Ga-doped ZnO source-drain electrodes

Abstract

In this study, transparent Ga-doped ZnO (GZO) films grown by magnetron sputtering were used as the source-drain (S-D) electrodes of bottom-contact organic field effect transistors (OTFTs). The GZO films exhibited good transmittance (beyond 80 %) in the visible region and the work functions of GZO films were found to be gradually increased with increasing the annealing temperature from 500 to 700 °C, leading to the reduction of contact barriers and improvement of device performances. OTFT fabricated by GZO S-D electrodes exhibited higher field-effect mobility of 0.0101 cm2/Vs and threshold voltage of −7.7 V when the GZO electrodes were annealed at 700 °C. To further increase the carrier injection, an ultra-thin CuPc film was used as the buffer layer prior to the deposition of Pentacene, and an increased mobility of 0.0257 cm2/vs was obtained. The results indicate that optimized transparent GZO films prepared by magnetron sputtering have great potential in the S-D electrodes of OTFTs.