Dependence of Sub-Thermionic Swing on Channel Thickness and Drain Bias of Poly-Si Junctionless Thin-Film Transistor

作者：Ma, William Cheng-Yu^*; Wang, Jia-Yi; Wang, Hsiao-Chun; Huang, Yan-Jia; Yu, Li-Wei

来源：IEEE Electron Device Letters, 2018, 39(8): 1122-1125.

DOI：10.1109/LED.2018.2850974

• Junctionless transistor
• ultra-thin body
• sub-60
• thin-film transistor

We demonstrate the polycrystalline-silicon (poly-Si) junctionless (JL) thin-film transistor (TFT) with a planar structure and an ultra-thin channel film thickness similar to 1.5-nm exhibiting subthreshold swing (S.S.) less than 60 mV/decade. The S.S. of the poly-Si JL-TFT shows abnormal drain-voltage dependence, which the higher drain voltage leads to the smaller S.S. The minimum S.S. (S.S.(min)) observed in this letter is about 30 mV/decade, which is a record low S.S.(min). The sub-60-mV/decade S.S. of the poly-Si JL-TFT is attributed to the impact ionization effect resulting from the high lateral electric field at the drain side at OFF-state. It is different from the conventional inversion-mode transistor, whose pinch-off point is observed at ON-state rather than the OFF-state. The lateral electric field is also found to be increasing with decreasing the channel thickness, and as a consequence, the impact ionization effect is more pronounced when the channel thickness is thinner. This letter shows a new concept for JL transistors, which would be helpful for the development of poly-Si JL-TFTs and the applications of 3-D integrated circuit and non-volatile memory.

• 出版日期2018-8
• 单位中山大学