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

Abstract

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 50 μm. The fabricated TFTs are annealed at 500 °C in air. The TFTs exhibit a field effect mobility 0.58 (cm2 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 106.