基于高迁移率微晶硅的薄膜晶体管

摘要

Microcrystalline silicon (μc-Si: H) has recently been proven to be a promising material for thin- film transistors (TFTs). We present μc-Si.H TFTs fabricated by plasma-enhanced chemical vapor deposi-tion at temperatures below 200℃ in a condition similar to the fabrication of amorphous silicon TFTs. The μc-Si. H TFTs exhibit device mobilities exceeding 30 cm2/Vs and threshold voltages in the range of 2.5 V.Such high mobilities are observed for long channel devices (50～200 μm). For short channel device (2μm), the mobility reduces to 7 cm2/Vs. Furthermore the threshold voltage of the TFTs decreases with de-creasing channel length. A simple model is developed, which explains the observed reduction of the device mobility and threshold voltage with decreasing channel length by the influence of drain and source contact resistance.%近年来,微晶硅(μc-Si:H)被认为是一种制作 TFT 的有前景的材料.采用PECVD法,在低于200℃时制作了微晶硅TFTs,其制作条件类似于非晶态 TFTs.微晶硅 TFTs 器件的迁移率超过了 30 cm2/Vs,而阈值电压是 2.5 V.在长沟道器件(50～200 μm)中观测到了这种高迁移率.但对于短沟道器件(2 μm),迁移率就降低到了7 cm2/Vs.此外,该 TFTs 的阈值电压随着沟道长度的减少而增大.文章采用了一种简单模型解释了迁移率、阈值电压随着沟道长度的缩短而分别减少、增加的原因在于源漏接触电阻的影响.