ZnO TFTs prepared by chemical bath deposition technique with high-k La2O3 gate dielectric annealed in ambient atmosphere

In this paper, the electrical properties of top-gated thin-film transistors with low-cost chemical bath deposition (CBD) of ZnO as active material and a high-k rare-earth oxide La2O3 as gate dielectric have been reported. The source-drain and gate electrodes and dielectric layers are fabricated by thermal evaporation techniques in high vacuum of the order of 10(-6)Torr in a coplanar electrode structure. The channel length of the TFT is of 50m. The fabricated TFTs are annealed at 500 degrees C in air. The TFTs exhibit a field effect mobility 0.58 (cm(2)V(-1)s(-1)). Use of a high dielectric constant (high-k) gate insulator reduces the threshold voltage and subthreshold swing of the TFTs. The TFTs exhibit a low threshold voltage of 4V. The calculated values of gain-bandwidth product and subthreshold swing are also evaluated and presented. The ON/OFF ratio of the TFT is found to be 10(6).