Degradation of low temperature polycrystalline silicon thin film transistors under negative bias temperature instability stress with illumination effect

Chia Sheng Lin*, Ying Chung Chen, Ting Chang Chang, Hung Wei Li, Wei Che Hsu, Shih Ching Chen, Ya-Hsiang Tai, Fu Yen Jian, Te Chih Chen, Kuan Jen Tu, Hsing Hua Wu, Yi Chan Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

This work investigates negative bias temperature instability (NBTI) in low temperature polycrystalline silicon thin film transistors (LTPS TFTs) in a darkened and in an illuminated environment of different light intensities. Experimental results reveal that the generations of interface state density (Nit) are identical under various illuminated intensity NBTI stresses. Nevertheless, the degradation of the grain boundary trap (N trap) under illumination was more significant than that for the darkened environment, with degradation increasing as illumination intensity increases. This phenomenon is mainly caused by the extra number of holes generated during the illuminated NBTI stress. The increased Ntrap degradation leads to an increase in the darkened environment leakage current. This indicates that more traps are generated in the drain junction region than from carrier tunneling via the trap, resulting in leakage current. Conversely, an increase in Ntrap degradation results in a decrease in the photoleakage current. This indicates that the number of recombination centers increases in the poly-Si bulk, affecting photosensitivity in LTPS TFTs.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume157
Issue number2
DOIs
StatePublished - 15 Jan 2010

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