A Unified Physics-Based Model for Analyzing Hysteresis in Organic Thin-Film Transistors

Hysteresis effects are often observed in voltage sweeps of organic thin-film transistors (OTFTs), resulting in threshold voltage shifts. While commonly associated with bias stress effects, the origins of hysteresis are diverse, with limited scientific studies providing a complete understanding of hysteresis in OFETs. Here, we use a physics-based model for organic thin film to investigate the hysteresis effects in OTFTS. Unlike many previous studies, our model allows for a more in-depth investigation of this phenomenon. Our method demonstrates a strong agreement between measurement and the model using parameter values obtained through the extraction process given by the unified modeling and extraction method (UMEM). In our quantitative analysis, we examined the hysteresis behavior in transistors of different channel lengths. For a transistor with a channel length of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$200~\mu $ </tex-math></inline-formula> m, the threshold voltage shift (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {V} _{\mathrm {T}}$ </tex-math></inline-formula>) between backward and forward sweeps was 0.15 V. In contrast, for a transistor with a channel length of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu $ </tex-math></inline-formula> m, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {V} _{\mathrm {T}}$ </tex-math></inline-formula> was observed to be 0.3 V. In addition, we observed that the characteristics temperature (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$T_{0}$ </tex-math></inline-formula>) of the density of states (DOSs) increases, which impacts the trapping behavior.