Bias-induced threshold voltages shifts in thin-film organic transistors

Gomes, Henrique L.; Stallinga, Peter; Dinelli, Franco; Murgia, Mauro; Biscarini, Fabio; Leeuw, Dago M. de; Muck, T.; Geurts, J.; Molenkamp, L. W.; Wagner, Veit

doi:10.1063/1.1713035

Cited by 190 publications

(109 citation statements)

References 21 publications

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“…Under vacuum conditions, with practically no water present on the SiO 2 interface, the bias-stress effect is greatly slowed down. 6,11,20,21 This is evident from the relaxation time of =2ϫ 10 6 s obtained from the bias-stress measurements on a similar PTAA transistor in vacuum, 11 which is more than two orders of magnitude larger than the above value in ambient. Furthermore, pretreatment of the SiO 2 with hydrophobic HMDS or octadecyltrichlorosilane is is known to decelerate the effect.…”

Section: Bias-stress Effect: Experimentalmentioning

confidence: 73%

“…2͑a͒ show the thresholdvoltage shift ⌬V th ͑t͒ = V th 0 − V th ͑t͒ as a function of time t. Here, V th 0 is the threshold voltage shift at the start of the experiment, which is close to zero. In studies of the bias-stress effect it has become customary to describe the shift ⌬V th ͑t͒ with a stretched-exponential function, 6,11,16 ⌬V th ͑t͒ = V 0 ͑1 − exp͓−͑t / ͒ ␤ ͔͒, where the prefactor V 0 is close to ͉V G0 ͉, is a relaxation time, and 0 Ͻ ␤ Ͻ 1 an exponent. As can be seen in Fig.…”

Section: Bias-stress Effect: Experimentalmentioning

confidence: 99%

“…[5][6][7][8][9][10][11][12][13][14] SiO 2 is chosen to prevent effects of ionic movements, which are known to occur in organic gate dielectrics. 15 Nevertheless, transistors with SiO 2 as gate dielectric suffer from the bias-stress effect.…”

Section: Introductionmentioning

confidence: 99%

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Proton migration mechanism for operational instabilities in organic field-effect transistors

et al. 2010

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. (2010). Proton migration mechanism for operational instabilities in organic field-effect transistors. Physical Review B, 82(7), 075322-1/11. [075322]. DOI: 10.1103/PhysRevB.82.075322 DOI:10.1103/PhysRevB.82.075322 Document status and date:Published: 01/01/2010 Document Version:Publisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement: Organic field-effect transistors exhibit operational instabilities involving a shift of the threshold gate voltage when a gate bias is applied. For a constant gate bias the threshold voltage shifts toward the applied gate bias voltage, an effect known as the bias-stress effect. Here, we report on a detailed experimental and theoretical study of operational instabilities in p-type transistors with silicon-dioxide gate dielectric both for a constant as well as for a dynamic gate bias. We associate the instabilities with a reversible reaction in the organic semiconductor in which holes are converted into protons in the presence of water and a reversible migration of these protons into the gate dielectric. We show how redistribution of charge between holes in the semiconductor and protons in the gate dielectric can consistently explain the experimental observations. Furthermore, we show how a shorter period of application of a gate bias leads to a faster backward shift of the threshold voltage when the gate bias is removed. The proposed mechanism is consistent with the observed acceleration of the bias-stress effect with increasing humidity, increasing temperature, and increasing energy of the highest molecular orbital of the org...

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Section: Bias-stress Effect: Experimentalmentioning

confidence: 73%

Section: Bias-stress Effect: Experimentalmentioning

confidence: 99%

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Proton migration mechanism for operational instabilities in organic field-effect transistors

et al. 2010

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“…Stress effects are commonly reported in the literature for a variety of transistors prepared using different techniques, different dielectric layers, as well as different organic semiconductors. [1][2][3][4][5][6][7] The effect has been explained as due to a slow trapping of charge carriers in defects of unknown origin. 3 It is known that the current degradation is faster when the devices are exposed to water vapor atmosphere, 4 moreover it has been also reported that the device electrical stability improves after heating the devices in high vacuum.…”

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Electrical instabilities in organic semiconductors caused by trapped supercooled water

Gomes

Stallinga

Cölle

et al. 2006

Applied Physics Letters

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It is reported that the electrical instability known as bias stress is caused by the presence of trapped water in the organic layer. Experimental evidence as provided by the observation of an anomaly occurring systematically at around 200K. This anomaly is observed in a variety of materials, independent of the deposition techniques and remarkably coincides with a known phase transition of supercooled water. Confined water does not crystallize at 273K but forms a metastable liquid. This metastable water behaves electrically as a charge trap, which causes the instability. Below 200K the water finally solidifies and the electrical traps disappear.

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“…The shift in threshold voltage leads to a monotonically decreasing source-drain current. Experimentally, it has been shown that the threshold-voltage shift follows a stretchedexponential time dependence [4][5][6] as given by DV th ðtÞ ¼ ðV G À V th;0 Þð1 À exp½Àðt=sÞ b Þ;…”

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Influence of the semiconductor oxidation potential on the operational stability of organic field-effect transistors

Sharma

Mathijssen

Bobbert

et al. 2011

Applied Physics Letters

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During prolonged application of a gate bias, organic field-effect transistors show a gradual shift of the threshold voltage towards the applied gate bias voltage. The shift follows a stretched-exponential time dependence governed by a relaxation time. Here, we show that a thermodynamic analysis reproduces the observed exponential dependence of the relaxation time on the oxidation potential of the semiconductor. The good fit with the experimental data validates the underlying assumptions. It demonstrates that this operational instability is a straightforward thermodynamically driven process that can only be eliminated by eliminating water from the transistor.

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Bias-induced threshold voltages shifts in thin-film organic transistors

Cited by 190 publications

References 21 publications

Proton migration mechanism for operational instabilities in organic field-effect transistors

Proton migration mechanism for operational instabilities in organic field-effect transistors

Electrical instabilities in organic semiconductors caused by trapped supercooled water

Influence of the semiconductor oxidation potential on the operational stability of organic field-effect transistors

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