ZnO TFTs prepared by chemical bath deposition technique with high‐ k La 2 O 3 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 La 2 O 3 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 50 μm. The fabricated TFTs are annealed at 500 °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 4 V. 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 .