Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation

Abstract We report on the appearance of a strong persistent photoconductivity (PPC) and conductor-like behaviour in zinc tin oxide (ZTO) thinfilm phototransistors. The active ZTO channel layer was prepared by remote plasma reactive sputtering and possesses an amorphous structure. Under sub-bandgap e...

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Autores principales:	Soumen Dhara, Kham M. Niang, Andrew J. Flewitt, Arokia Nathan, Stephen A. Lynch
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/e13187abd71a463dad0e4e576bcde901
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spelling	oai:doaj.org-article:e13187abd71a463dad0e4e576bcde9012021-12-02T18:48:09ZTail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation10.1038/s41598-021-98339-42045-2322https://doaj.org/article/e13187abd71a463dad0e4e576bcde9012021-09-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-98339-4https://doaj.org/toc/2045-2322Abstract We report on the appearance of a strong persistent photoconductivity (PPC) and conductor-like behaviour in zinc tin oxide (ZTO) thinfilm phototransistors. The active ZTO channel layer was prepared by remote plasma reactive sputtering and possesses an amorphous structure. Under sub-bandgap excitation of ZTO with UV light, the photocurrent reaches as high as ~ 10−4 A (a photo-to-dark current ratio of ~ 107) and remains close to this high value after switching off the light. During this time, the ZTO TFT exhibits strong PPC with long-lasting recovery time, which leads the appearance of the conductor-like behaviour in ZTO semiconductor. In the present case, the conductivity changes over six orders of magnitude, from ~ 10−7 to 0.92/Ω/cm. After UV exposure, the ZTO compound can potentially remain in the conducting state for up to a month. The underlying physics of the observed PPC effect is investigated by studying defects (deep states and tail states) by employing a discharge current analysis (DCA) technique. Findings from the DCA study reveal direct evidence for the involvement of sub-bandgap tail states of the ZTO in the strong PPC, while deep states contribute to mild PPC.Soumen DharaKham M. NiangAndrew J. FlewittArokia NathanStephen A. LynchNature 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 Soumen Dhara Kham M. Niang Andrew J. Flewitt Arokia Nathan Stephen A. Lynch Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
description	Abstract We report on the appearance of a strong persistent photoconductivity (PPC) and conductor-like behaviour in zinc tin oxide (ZTO) thinfilm phototransistors. The active ZTO channel layer was prepared by remote plasma reactive sputtering and possesses an amorphous structure. Under sub-bandgap excitation of ZTO with UV light, the photocurrent reaches as high as ~ 10−4 A (a photo-to-dark current ratio of ~ 107) and remains close to this high value after switching off the light. During this time, the ZTO TFT exhibits strong PPC with long-lasting recovery time, which leads the appearance of the conductor-like behaviour in ZTO semiconductor. In the present case, the conductivity changes over six orders of magnitude, from ~ 10−7 to 0.92/Ω/cm. After UV exposure, the ZTO compound can potentially remain in the conducting state for up to a month. The underlying physics of the observed PPC effect is investigated by studying defects (deep states and tail states) by employing a discharge current analysis (DCA) technique. Findings from the DCA study reveal direct evidence for the involvement of sub-bandgap tail states of the ZTO in the strong PPC, while deep states contribute to mild PPC.
format	article
author	Soumen Dhara Kham M. Niang Andrew J. Flewitt Arokia Nathan Stephen A. Lynch
author_facet	Soumen Dhara Kham M. Niang Andrew J. Flewitt Arokia Nathan Stephen A. Lynch
author_sort	Soumen Dhara
title	Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
title_short	Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
title_full	Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
title_fullStr	Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
title_full_unstemmed	Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
title_sort	tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/e13187abd71a463dad0e4e576bcde901
work_keys_str_mv	AT soumendhara tailstatemediatedconductioninzinctinoxidethinfilmphototransistorsunderbelowbandgapopticalexcitation AT khammniang tailstatemediatedconductioninzinctinoxidethinfilmphototransistorsunderbelowbandgapopticalexcitation AT andrewjflewitt tailstatemediatedconductioninzinctinoxidethinfilmphototransistorsunderbelowbandgapopticalexcitation AT arokianathan tailstatemediatedconductioninzinctinoxidethinfilmphototransistorsunderbelowbandgapopticalexcitation AT stephenalynch tailstatemediatedconductioninzinctinoxidethinfilmphototransistorsunderbelowbandgapopticalexcitation
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Tail state mediated conduction in zinc tin oxide thinfilm phototransistors under below bandgap optical excitation

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