Achieving High Performance Oxide TFT-Based Inverters by Use of Dual-Gate Configurations With Floating and Biased Secondary Gates

A dual-gate thin-film transistor (TFT) has two gate electrodes. In inverted, staggered TFTs, the primary gate is usually the bottom gate (BG) and the TFT's threshold voltage (VTH) can be adjusted by applying a constant bias to the secondary gate, the top gate (TG), while scanning the BG. Dual-gate TFTs are being used as the load TFT in oxide semiconductor-based inverters, where the TG is biased positively to shift the VTH negatively and, thereby improving the inverter's output swing. Here, we show that the same can be achieved by the use of a floating TG. Furthermore, we show that the noise margin of the inverter can also be controlled by adding a biased TG to the driving TFT.