Anomalous Kink Effect Induced by Bottom-Shield-Metal in LTPS TFTs on Plastic Substrates

Ki Woo Kim, Jongseuk Kang, Hoewoo Ku, Kyungho Lee, Hyun Jae Kim

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11 Citations (Scopus)


The anomalous kink effect was investigated in n-type low-temperature polycrystalline silicon thin-film transistors with the source-contacted bottom-shield-metal (SBSM) layer on a polyimide substrate. Using experiments and technology computer-aided design simulation, it was found that the SBSM layer plays a critical role in the anomalous kink effect. The SBSM layer modulated the carrier concentration within the lightly doped drain (LDD) region according to the applied drain voltage (VDS). In addition, this carrier modulation caused changes in the lateral electric field at simultaneously the channel/LDD junction and the LDD/n+ junction. Thus, multiple kink effects, different from the conventional kink effect, occurred in two different VDS regions with different slopes depending on the LDD length (LLDD) and the overlap length (LBSM) between the LDD region and the SBSM layer in the drain region. We propose a novel asymmetric design to suppress the SBSM-induced anomalous kink effect in all VDS regimes. This design has the following requirements with respect to LLDD and LBSM at the drain region: LBSM greater than 1.0 μm,LLDD-LBSM (LLDD) greater than 1.0 μm, and LBSM equal to half of LLDD.

Original languageEnglish
Article number8451896
Pages (from-to)1524-1527
Number of pages4
JournalIEEE Electron Device Letters
Issue number10
Publication statusPublished - 2018 Oct

Bibliographical note

Funding Information:
Manuscript received August 15, 2018; accepted August 21, 2018. Date of publication August 30, 2018; date of current version September 25, 2018. This work was supported by the LG Display and the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIT) No. 2017R1A2B3008719. The review of this letter was arranged by Editor S. Chang. (Corresponding author: Hyun Jae Kim.) K. W. Kim is with the Department of Electrical and Electronic Engineering, Yonsei University, Seoul 03722, South Korea, and also with the R&D Center, LG Display Co., Ltd., Gyeonggi-Do 413-811, South Korea.

Publisher Copyright:
© 1980-2012 IEEE.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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