The effects of electric field and gate bias pulse on the migration and stability of ionized oxygen vacancies in amorphous In-Ga-Zn-O thin film transistors

Oxygen vacancies have been considered as the origin of threshold voltage instability under negative bias illumination stress in amorphous oxide thin film transistors. Here we report the results of first-principles molecular dynamics simulations for the drift motion of oxygen vacancies. We show that...

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Bibliographic Details
Published in:Science and technology of advanced materials 2015-06, Vol.16 (3), p.034902-34908
Main Authors: Oh, Young Jun, Noh, Hyeon-Kyun, Chang, Kee Joo
Format: Article
Language:English
Subjects:
amorphous In-Ga-Zn-O
Bias
Computer simulation
density functional theory
Electric fields
First principles
Focus on Advanced Inorganic Materials Science: Non-Traditional Concepts and Approaches
Gates
Hole traps
Indium gallium zinc oxide
Molecular dynamics
oxide thinfilm transistor
Oxygen
oxygen vacancy
Photoconductivity
Semiconductor devices
Stability
Thin film transistors
Thin films
Threshold voltage
Transistors
Vacancies
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Summary:Oxygen vacancies have been considered as the origin of threshold voltage instability under negative bias illumination stress in amorphous oxide thin film transistors. Here we report the results of first-principles molecular dynamics simulations for the drift motion of oxygen vacancies. We show that oxygen vacancies, which are initially ionized by trapping photoexcited hole carriers, can easily migrate under an external electric field. Thus, accumulated hole traps near the channel/dielectric interface cause negative shift of the threshold voltage, supporting the oxygen vacancy model. In addition, we find that ionized oxygen vacancies easily recover their neutral defect configurations by capturing electrons when the Fermi level increases. Our results are in good agreement with the experimental observation that applying a positive gate bias pulse of short duration eliminates hole traps and thus leads to the recovery of device stability from persistent photoconductivity.
ISSN:1468-6996
1878-5514
DOI:10.1088/1468-6996/16/3/034902