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

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 degrees 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 cm(2)/Vs and threshold voltage of - 7.7 V when the GZO electrodes were annealed at 700 degrees 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 cm(2)/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.