Abnormal Hump Effect Induced by Hydrogen Diffusion during Self-Heating Stress in Top-Gate Amorphous InGaZnO TFTs

Hong Chih Chen, Jian Jie Chen, Yu Fa Tu, Kuan Ju Zhou, Chuan Wei Kuo, Wan Ching Su, Yang Hao Hung, Yu Shan Shih, Hui Chun Huang, Tsung Ming Tsai, Jen Wei Huang, Wei Chih Lai, Ting Chang Chang

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9 Citations (Scopus)


The mechanism of hydrogen-diffusion-induced electrical degradation under the self-heating effect for a top-gate amorphous InGaZnO (a-IGZO) thin-film transistor is examined in this article. Joule heating occurs in channels under high operating currents. The hydrogen in the \text{n}^{+} a-IGZO source/drain then diffuses into the channel and shifts the threshold voltage ( {V}_{{\text {TH}}} ) in the negative direction. As the thermal conductivity of a-IGZO is lower than that of the surrounding insulator, the heat is preferentially dissipated from the sides of the channel. However, the heat in the center of the channel cannot by dissipated quickly. In addition, the unequal channel thermal effect induces a hump effect in the electrical characteristics, which is observed in COMSOL simulations. Hydrogen diffusion under self-heating stress (SHS) operation increases both the effective channel length and parasitic capacitance. The capacitance measurement method is used to clarify the mechanisms of these abnormal phenomena. Finally, the Joule heating effect is eliminated in a low-temperature environment at 200 K with a constant current, confirming that the degradation is indeed caused by the Joule heating effect.

Original languageEnglish
Article number9102381
Pages (from-to)2807-2811
Number of pages5
JournalIEEE Transactions on Electron Devices
Issue number7
Publication statusPublished - 2020 Jul

All Science Journal Classification (ASJC) codes

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


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