This work investigates the transient current in the subthreshold region of a low-temperature polycrystalline silicon thin-film transistor (LTPS TFT) on a polyimide (PI) substrate. The measurement of this current shows an instability that is not seen in the device on a glass substrate; the instability appears as a current variation under constant voltage and overshoot or undershoot under external stress voltage transitions. To explain this effect for a TFT on a PI substrate, a transient body effect (TBE) is suggested due to a threshold voltage shift caused by the charge distribution inside the substrate. A SPICE model is proposed based on this concept, and it shows excellent agreement with device measurements. The model offers a simulation guideline for LTPS TFTs on PI substrates.

这项工作研究在聚酰亚胺（PI）基板上的低温多晶硅薄膜晶体管（LTPS TFT）的亚阈值区域中的瞬态电流。测量该电流显示出不稳定性，这在玻璃基板上的设备中看不到。不稳定性表现为恒定电压下的电流变化，以及外部应力电压转换下的过冲或下冲。为了解释PI基板上TFT的这种效果，由于基板内部电荷分布引起的阈值电压偏移，建议采用瞬态体效应（TBE）。基于此概念提出了一个SPICE模型，该模型显示出与器件测量的极佳一致性。该模型为PI基板上的LTPS TFT提供了仿真指南。