Analysis of anomalous capacitance induced by TAGIDL in p-channel LTPS TFTs

Chia Sheng Lin*, Ying Chung Chen, Ting Chang Chang, Hung Wei Li, Shih Ching Chen, Fu Yen Jian, Ying Shao Chuang, Te Chih Chen, Yu Chun Chen, Ya-Hsiang Tai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


In this work, a mechanism of anomalous capacitance in p-channel low temperature polycrystalline silicon thin film transistors (LTPS TFTs) was investigated. In general, the effective capacitance of the LTPS TFTs was only dependent with the overlap area between the gate and source/drain under the off-state. However, the experimental results reveal that the off-state capacitance was increased with decreasing measurement frequency and/or with increasing measurement temperature. By fitting the curve of the drain current vs electric field under off-state region, it was verified that the trap-assisted gate-induced drain leakage (TAGIDL) consists of the Pool-Frenkel emission and thermal field emission. In addition, the charge density calculated from the Cgsd-Vg measurement also has the same dependence with electric field. This result demonstrates that the anomalous capacitance is mainly due to the TAGIDL. To suppress the anomalous capacitance, a band-to-band hot electron stress was utilized to reduce the vertical electric field between the gate and the drain. The electric field simulation was also performed by TCAD software.

Original languageEnglish
JournalJournal of the Electrochemical Society
Issue number11
StatePublished - 13 Oct 2010

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