Analysis of Photon-Induced Drain Current in Polycrystalline-Silicon Thin-Film Transistors
Analysis of Photon-Induced Drain Current in Polycrystalline-Silicon Thin-Film Transistors
复制标题
多晶硅薄膜晶体管中光子感应漏电流的分析
DOI：
10.1143/jjap.48.101201
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
H. Ikeda and N. Sano
中科院分区：
文献类型：
--
作者：
小松辰実;須田良幸;H. Ikeda and N. Sano
通过测量和器件模拟的方法研究了照明多晶硅薄膜晶体管的电学特性。在n沟道多晶硅TFT中发现了几个特征：平带电压(VFB)向正方向移动约0.1V，陷阱密度在中间禁带附近增加。在导通状态下，由于施主类型的增加和受主类型陷阱密度的减少，晶界势垒高度略有降低。在关态时，pn结漏极边缘的反向电流远大于产生电流或栅感漏极漏电流，几乎与光强成线性关系。在Vfb以下的关断电流中出现一个驼峰，这是由于载流子输运从关态pn结处的反向扩散向导通状态下的漂移扩散转变而产生的。考虑到这些特点，提出了一种基于表面电势的漏电流模型。通过改变光强或漏极电压，将该模型的计算结果与器件模拟和测量结果进行了比较。它们之间的良好一致性证实了该模型的有效性。
The electrical properties of illuminated polycrystalline-silicon thin-film transistors (poly-Si TFTs) were investigated by measurement and device simulation. Several features were revealed in n-channel poly-Si TFTs: the flat-band voltage (V fb) shifts to a positive direction on the order of 0.1 V. The trap density increases around the midgap. In the on-state, the grain boundary barrier height slightly decreases owing to the increase in donor-type and the decrease in acceptor-type trap densities. In the off-state, the reverse current of pn-junction at the drain edge becomes much larger than the generation current or gate-induced drain leakage current, showing almost linear dependence on light intensity. A hump appears in off-current below V fb, which is derived from the transition of carrier transport from the reverse diffusion at pn-junction in the off-state to the drift-diffusion in the on-state. Considering all these features, a surface-potential-based drain current model was proposed. Calculations using the model were compared with device simulation and measurement by varying the light intensity or drain voltage. The good agreements between them confirm the validity of the model.