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

Abstract

. (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...

Dynamics of charge carrier trapping in NO2 sensors based on ZnO field-effect transistors

“…It has been reported that the time scale for recovery then depends on the extent of stressing [22]. Here we have investigated the recovery of the ZnO transistors as a function of the trapped charge density.…”

Influence of film structure and light on charge trapping and dissipation dynamics in spun-cast organic thin-film transistors measured by scanning Kelvin probe microscopy

“…[11][12][13][14] Proximal probe techniques, such as scanning Kelvin probe microscopy (SKPM), allow us to fully explore the structure-property relationships in working OTFT structures. [14][15][16][17][18][19][20][21][22][23][24][25] SKPM provides the ability to monitor changes in charge transport phenomena in both space and time, a capability not afforded by traditional electrical performance measurements a Author to whom correspondence should be addressed.…”

Bias stress effect in polyelectrolyte-gated organic field-effect transistors

“…The fast saturation of the threshold voltage shift and the recovery time in EGOFETs is attributed to the large diffusion constant of protons in PSS as compared to SiO 2 (D $ 10 À19 m 2 s À1 ). 12,34 The migration of protons leads to the accumulation of protons in the gate insulator, which partially screens the applied gate voltage by creating an electric field that is compensated for by the gate voltage in order for an accumulation layer to be formed, and thus the threshold voltage of the OFET increases. Longer periods of time of the gate voltage application leads to larger number of holes converted into protons, and hence a larger increase or shift in the threshold voltage.…”

“…8,12,21,29 The mechanism proposed by several authors implies an electron transfer from adsorbed water present at the semiconductor/SiO 2 interface to positively charged semiconducting channel in the transistor (P3HT þ ). The products of the water oxidation are a proton and a dioxygen…”

“…There are various factors that can contribute to this observed instability where the main one is charge trapping 5 that could occur either in the insulator, 6 in the semiconductor, [7][8][9] or at the semiconductor/insulator interface. 10,11 Other suggested mechanisms include variation of contact resistance under gate bias, 5 a minor electrical leakage or ionic displacements in gate insulators, 12 and humidity effect on gate insulator properties. 13 The presence of active trapping sites due to intrinsic structural defects (gate insulator/organic semiconductor interface 14,15 and disordered gate insulator 6 ) or impurities (water or oxygen) 16 has been identified as one of the main causes behind bias stress.…”