An Analytical Model for Dual Gate Piezoelectrically Sensitive ZnO Thin Film Transistors

Highly sensitive force sensors of piezoelectric zinc oxide (ZnO) dual-gate thin film transistors (TFTs) are reported together with an analytical model that elucidates the physical origins of their response. The dual-gate TFTs are fabricated on a polyimide substrate and exhibited a field effect mobility of approximate to 5 cm(2) V-1 s(-1), I-max/I-min ratio of 10(7), and a subthreshold slope of 700 mV dec(-1), and demonstrated static and transient current changes under external forces with varying amplitude and polarity in different gate bias regimes. To understand the current modulation of the dual-gate TFT with independently biased top and bottom gates, an analytical model is developed. The model includes accumulation channels at both surfaces and a bulk channel within the film and accounts for the force-induced piezoelectric charge density. The microscopic piezoelectric response that modulates the energy-band edges and correspondent current-voltage characteristics are accurately portrayed by this model. Finally, the field-tunable force response in single TFT is demonstrated as a function of independent bias for the top and bottom gates with a force response range from -0.29 to 22.7 nA mN(-1). This work utilizes intuitive analytical models to shed light on the correlation between the material properties with the force response in piezoelectric TFTs.

Automated summary

Highly sensitive force sensors of piezoelectric zinc oxide dual-gate thin film transistors are reported, along with an analytical model that elucidates the physical origins of their response. The dual-gate TFTs exhibited static and transient current changes under external forces, with an analytical model accurately portraying the piezoelectric response that modulates the energy-band edges and current-voltage characteristics. Demonstrating a field-tunable force response in single TFT, this work sheds light on the correlation between material properties and the force response in piezoelectric TFTs.