Integrated TCAD modeling of channel optimization and contact-driven hydrogen sensing in ZnO TFTs

In order to examine the impact of channel dimensions on the electrical performance and hydrogen sensing behavior of zinc oxide (ZnO) thin-film transistors (TFTs), this work presents a TCAD-based modeling and simulation study that is validated experimentally. An optimized TFT structure is found by analyzing the effects of channel length and channel thickness on important device characteristics using a physically calibrated device model that incorporates suitable carrier transport and defect-state models. The findings show that by offering a suitable balance between gate control and carrier transport, careful channel engineering greatly enhances the electrical performance of ZnO TFTs. Palladium (Pd) source/drain contacts are then used to extend the optimized device to hydrogen sensing applications. By using calibrated Pd work-function modulation to model hydrogen exposure, the resulting Schottky-barrier variation and its impact on the device response can be analyzed. Hydrogen sensing is primarily controlled by contact-barrier modulation at the Pd/ZnO interface, according to the simulated sensing characteristics, which exhibit good agreement with experimental observations. Overall, this work provides valuable insights for the design of high-performance, low-power ZnO TFTs and multifunctional gas-sensing devices by establishing a physically consistent and experimentally validated TCAD framework that combines channel-dimension optimization with contact-engineered hydrogen sensing.