Operation Mechanisms of Flexible RF Silicon Thin Film Transistor under Bending Conditions

Abstract

We fabricate a flexible silicon thin-film transistor (TFT) on a plastic substrate as a key component and representative example to analyze the major influencing factors of flexible devices under bending conditions. Experimental and two-dimensional device modeling results reveal that bending radius and device dimensions have a significant influence on the radio-frequency (RF) performance of the flexible silicon nanomembrane (SiNM) TFT under bending conditions. Carrier mobility and electric field extracted from the model, together with theoretical analysis, were employed to study the performance dependence and the operation mechanisms of the bended TFTs. The carrier mobility and electric field are increased monotonically with larger bending strains, which lead to better RF performance. They also showed a consistent change trend with different device parameters (e.g., gate length, oxide thickness). Flexible SiNM TFTs with a smaller gate length and a larger gate dielectric thickness are shown to have better RF performance robustness with bending strains. The analysis provides a guideline for the study of flexible electronics under bending conditions.