非晶硅薄膜晶体管关态电流的物理模型

Physical model for the off current in amorphous silicon thin film transistors

基于器件有源层内纵向电场变化模型,提出了背沟界面能带弯曲量与栅源电压的近似方程,并针对背沟电子传导机制建立器件反向亚阈电流模型;基于空穴的一维连续性方程,提出有源层内空穴逃逸率的物理模型,并针对前沟空穴传导机制建立器件泄漏电流模型.实验结果验证了所提关态电流物理模型的准确性,曲线拟合良好.

A physical model for the off current in amorphous silicon thin film transistors is proposed. Firstly,an approximation for the band bending in the back interface as a function of the gate-source voltage is derived in the reverse subthreshold region,and then a current model due to electron conduction in the back channel is developed by considering the deep states.Secondly,a rate used to describe the escaping possibility of holes in the bulk a-Si：H layer is proposed based on the one-dimensional continuity equation. By considering the hole generation rate in the drain depletion region and the hole escaping rate in the bulk a-Si：H layer,a leakage current model due to hole conduction in the front channel is developed.The proposed model has been verified using the experimental data.