Origin of light instability in amorphous IGZO thin-film transistors and its suppression

Abstract Radiating amorphous In–Ga–Zn–O (a-IGZO) thin-film transistors (TFTs) with deep ultraviolet light (λ = 175 nm) is found to induce rigid negative threshold-voltage shift, as well as a subthreshold hump and an increase in subthreshold-voltage slope. These changes are attributed to the photo cr...

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Autores principales:	Mallory Mativenga, Farjana Haque, Mohammad Masum Billah, Jae Gwang Um
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/e4ca094ea88f4299b3a88c484b2fe35d
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spelling	oai:doaj.org-article:e4ca094ea88f4299b3a88c484b2fe35d2021-12-02T18:31:29ZOrigin of light instability in amorphous IGZO thin-film transistors and its suppression10.1038/s41598-021-94078-82045-2322https://doaj.org/article/e4ca094ea88f4299b3a88c484b2fe35d2021-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-94078-8https://doaj.org/toc/2045-2322Abstract Radiating amorphous In–Ga–Zn–O (a-IGZO) thin-film transistors (TFTs) with deep ultraviolet light (λ = 175 nm) is found to induce rigid negative threshold-voltage shift, as well as a subthreshold hump and an increase in subthreshold-voltage slope. These changes are attributed to the photo creation and ionization of oxygen vacancy states (VO), which are confined mainly to the top surface of the a-IGZO film (backchannel). Photoionization of these states generates free electrons and the transition from the neutral to the ionized VO is accompanied by lattice relaxation, which raises the energy of the ionized VO. This and the possibility of atomic exchange with weakly bonded hydrogen leads to metastability of the ionized VO, consistent with the rigid threshold-voltage shift and increase in subthreshold-voltage slope. The hump is thus a manifestation of the highly conductive backchannel and its formation can be suppressed by reduction of the a-IGZO film thickness or application of a back bias after radiation. These results support photo creation and ionization of VO as the main cause of light instability in a-IGZO TFTs and provide some insights on how to minimize the effect.Mallory MativengaFarjana HaqueMohammad Masum BillahJae Gwang UmNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Mallory Mativenga Farjana Haque Mohammad Masum Billah Jae Gwang Um Origin of light instability in amorphous IGZO thin-film transistors and its suppression
description	Abstract Radiating amorphous In–Ga–Zn–O (a-IGZO) thin-film transistors (TFTs) with deep ultraviolet light (λ = 175 nm) is found to induce rigid negative threshold-voltage shift, as well as a subthreshold hump and an increase in subthreshold-voltage slope. These changes are attributed to the photo creation and ionization of oxygen vacancy states (VO), which are confined mainly to the top surface of the a-IGZO film (backchannel). Photoionization of these states generates free electrons and the transition from the neutral to the ionized VO is accompanied by lattice relaxation, which raises the energy of the ionized VO. This and the possibility of atomic exchange with weakly bonded hydrogen leads to metastability of the ionized VO, consistent with the rigid threshold-voltage shift and increase in subthreshold-voltage slope. The hump is thus a manifestation of the highly conductive backchannel and its formation can be suppressed by reduction of the a-IGZO film thickness or application of a back bias after radiation. These results support photo creation and ionization of VO as the main cause of light instability in a-IGZO TFTs and provide some insights on how to minimize the effect.
format	article
author	Mallory Mativenga Farjana Haque Mohammad Masum Billah Jae Gwang Um
author_facet	Mallory Mativenga Farjana Haque Mohammad Masum Billah Jae Gwang Um
author_sort	Mallory Mativenga
title	Origin of light instability in amorphous IGZO thin-film transistors and its suppression
title_short	Origin of light instability in amorphous IGZO thin-film transistors and its suppression
title_full	Origin of light instability in amorphous IGZO thin-film transistors and its suppression
title_fullStr	Origin of light instability in amorphous IGZO thin-film transistors and its suppression
title_full_unstemmed	Origin of light instability in amorphous IGZO thin-film transistors and its suppression
title_sort	origin of light instability in amorphous igzo thin-film transistors and its suppression
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/e4ca094ea88f4299b3a88c484b2fe35d
work_keys_str_mv	AT mallorymativenga originoflightinstabilityinamorphousigzothinfilmtransistorsanditssuppression AT farjanahaque originoflightinstabilityinamorphousigzothinfilmtransistorsanditssuppression AT mohammadmasumbillah originoflightinstabilityinamorphousigzothinfilmtransistorsanditssuppression AT jaegwangum originoflightinstabilityinamorphousigzothinfilmtransistorsanditssuppression
_version_	1718378011950055424

Origin of light instability in amorphous IGZO thin-film transistors and its suppression

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