Vapor-phase deposition of the fluorinated copolymer gate insulator for the p-type organic thin-film transistor

Choi, Junhwan; Seong, Hyejeong; Pak, Kwanyong; Im, Seyoung

doi:10.1080/15980316.2016.1171803

Cited by 11 publications

(7 citation statements)

References 26 publications

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“…However, note that the amount of I D decrease was exceptionally small (less than 1.2% of initial I D up to 3000 s), compared to other reported OTFTs. Considering that the hydrophobic skin layer was mainly composed of hydrocarbon and there was no specific functionality that can reduce the I D decrease (e.g., fluorine), 21,62 we propose a hypothesis that −OH functionalities in the bulk polymer which are readily accommodate dipole polarization, 20,51 facilitate the accumulation of extra holes at the semiconductor/dielectric interface. With the prolonged CVS time, the I D tended to increase slightly (0.988 and 0.996 times of initial I D at 3000 and 6000 s, respectively) and even exceeded initial I D (1.005 and 1.039, 1.062 times of initial I D at 10 000, 30 000, and 50 000 s, respectively).…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Generation of a Molecular Thin Hydrophobic Skin Layer on a Sub-20 nm, High-k Polymer Dielectric for Extremely Stable Organic Thin-Film Transistor Operation

Choi

Yoon

Kim

et al. 2019

ACS Appl. Mater. Interfaces

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Polymer dielectric materials with hydroxyl functionalities such as poly(4-vinylphenol) and poly(vinyl alcohol) have been utilized widely in organic thin-film transistors (OTFTs) because of their excellent insulating performance gained by hydroxyl-mediated cross-linking. However, the polar hydroxyl functionality also deleteriously affects the performance of OTFTs and significantly impairs the device stability. In this study, a sub-20 nm, high-k copolymer dielectric with hydroxyl functionality, poly(2-hydroxyethyl acrylate-co-di(ethylene glycol) divinyl ether), was synthesized in the vapor phase via initiated chemical vapor deposition. The inherently dry environment offered by the vaporphase polymer synthesis prompted the snuggling of polar hydroxyl functionalities into the bulk polymer film to form a molecular thin hydrophobic skin layer at its surface, verified by near-edge X-ray absorption fine structure analysis. The chemical composition of the copolymer dielectric was optimized systematically to achieve high dielectric constant (k ≈ 6.2) as well as extremely low leakage current densities (less than 3 × 10 −8 A/cm 2 in the range of ±2 MV/cm) even with sub-20 nm thickness, leading to one of the highest capacitance (higher than 300 nF/cm 2 ) achieved by a single polymer dielectric to date. Exploiting the structural advantage of the cross-linked high-k polymer dielectric, high-performance OTFTs were obtained. Notably, the spontaneously formed molecular thin, hydrophobic skin layer in the copolymer film substantially suppressed the hysteresis in the transistor operation. The trap analysis also suggested the formation of bulk trap with a high energy barrier and sufficiently low trap densities at the semiconductor/dielectric interface, owing to the surface skin layer. Furthermore, the OTFTs with the −OH-containing copolymer dielectric showed an unprecedentedly excellent operational stability. No apparent OTFT degradation was observed up to 50 000 s of high constant voltage stress (corresponding to the applied electric field of 1.4 MV/ cm) because of the markedly suppressed interfacial trap density by the hydrophobic skin layer, together with the current compensation by the bulk hydroxyl functionalities. We believe that the surface modification-free, one-step polymer dielectric synthetic strategy will provide a new insight into the design of polymer dielectric materials for high-performance, low-power soft electronic devices with high operational stability.

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Section: Resultsmentioning

confidence: 99%

Spontaneous Generation of a Molecular Thin Hydrophobic Skin Layer on a Sub-20 nm, High-k Polymer Dielectric for Extremely Stable Organic Thin-Film Transistor Operation

Choi

Yoon

Kim

et al. 2019

ACS Appl. Mater. Interfaces

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“…They are characterized by a smooth surface and low-surface energy. Their surface roughness (RMS) is usually of a few nanometres [70,[75][76][77]. Because of its smooth surface, an OSC layer deposited is free from discontinuities.…”

Section: Organic Dielectric Materialsmentioning

confidence: 99%

Hybrid bilayer gate dielectric-based organic thin film transistors

Teja

Gupta

2019

Bull Mater Sci

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Organic thin film transistors (OTFTs) are key building blocks for flexible, low cost electronics systems. They provide a viable alternative for silicon-based electronics with added advantages of low cost and flexibility. However, few issues like high-operating voltage, low-switching speed, high-leakage current and reliability are still a challenge. The overall performance of an OTFT depends on organic semiconductors and gate dielectric interface. In this paper, we review the current status and trends in the choice of dielectric layer for OTFTs. As a starting point, the performance parameters of an OTFT and their dependence on the dielectric layer are briefly discussed. A variety of dielectric materials which includes high-k inorganic, organic, surface coated inorganics and nanocomposites are also presented. The advantages and drawbacks of each of these materials are discussed in detail. We reviewed the latest developments in the dielectric materials especially, self-assembled monolayers (SAMs), hybrid bilayers and nanocomposites. SAM-based OTFTs offer several advantages but shift in the threshold voltage remains a concern. Nanocomposites are a latest addition to the dielectric materials, which offer advantages like solution processing and improved dielectric constant but have a rough surface. A hybrid bilayer that incorporates the inorganic dielectric as a base layer and a thin polymer layer over it to improve the surface properties offers several desirable characteristics over the other choices. Hence, we propose that hybrid bilayer gate dielectrics shall play a pivotal role in improving the OTFT performance.

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“…In order to address these concerns, a one-step, solvent-free technique termed “initiated chemical vapor deposition” ( i CVD) was developed for gating the semiconducting MoS 2 in FETs. i CVD is a well-established all-dry vapor-phase deposition technique for fabricating ultrathin polymer films, which offers large-area scalability and is compatible with a high-throughput manufacturing process. − In this work, an i CVD-grown copolymer gate dielectric layer was synthesized and its application to 2D MoS 2 FETs was demonstrated. Four vinyl groups of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) monomers and cyclohexyl groups of cyclohexyl methacrylate (CHMA) monomers were introduced to enhance the electrical strength via the formation of a network structure and to reduce the charge trap densities, respectively.…”

Section: Introductionmentioning

confidence: 99%

Defect-Free Copolymer Gate Dielectrics for Gating MoS₂ Transistors

et al. 2018

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In this study, the poly (2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane-co-cyclohexyl methacrylate) [p(V4D4-co-CHMA)] copolymer was developed for use as a gate dielectric in molybdenum disulfide (MoS 2 ) field-effect transistors (FETs). The p(V4D4-co-CHMA) copolymer was synthesized via the initiated chemical vapor deposition (iCVD) of two types of monomers: 2,4,6,8-tetramethyl-2,4,6,8tetravinylcyclotetrasiloxane (V4D4) and cyclohexyl methacrylate (CHMA). Four vinyl groups of V4D4 monomers and cyclohexyl groups of CHMA monomers were introduced to enhance the electrical strength of gate dielectrics through the formation of a highly crosslinked network and to reduce the charge trap densities at the MoS 2 −dielectric interface, respectively. The iCVD-grown p(V4D4-co-CHMA) copolymer films yielded a dielectric constant of 2.3 and a leakage current of 3.8 × 10 −11 A/cm 2 at 1 MV/cm. The resulting MoS 2 FETs with p(V4D4-co-CHMA) gate dielectrics exhibited excellent electrical properties, including an electron mobility of 35.1 cm 2 /V s, a subthreshold swing of 0.2 V/dec, and an on−off current ratio of 2.6 × 10 6 . In addition, the environmental and operational stabilities of MoS 2 FETs with p(V4D4-co-CHMA) top-gate dielectrics were superior to those of devices with SiO 2 back-gate dielectrics. The use of iCVD-grown copolymer gate dielectrics as demonstrated in this study provides a novel approach to realizing next-generation two-dimensional electronics.

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Vapor-phase deposition of the fluorinated copolymer gate insulator for the p-type organic thin-film transistor

Cited by 11 publications

References 26 publications

Spontaneous Generation of a Molecular Thin Hydrophobic Skin Layer on a Sub-20 nm, High-k Polymer Dielectric for Extremely Stable Organic Thin-Film Transistor Operation

Spontaneous Generation of a Molecular Thin Hydrophobic Skin Layer on a Sub-20 nm, High-k Polymer Dielectric for Extremely Stable Organic Thin-Film Transistor Operation

Hybrid bilayer gate dielectric-based organic thin film transistors

Defect-Free Copolymer Gate Dielectrics for Gating MoS₂ Transistors

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Vapor-phase deposition of the fluorinated copolymer gate insulator for the p-type organic thin-film transistor

Cited by 11 publications

References 26 publications

Spontaneous Generation of a Molecular Thin Hydrophobic Skin Layer on a Sub-20 nm, High-k Polymer Dielectric for Extremely Stable Organic Thin-Film Transistor Operation

Spontaneous Generation of a Molecular Thin Hydrophobic Skin Layer on a Sub-20 nm, High-k Polymer Dielectric for Extremely Stable Organic Thin-Film Transistor Operation

Hybrid bilayer gate dielectric-based organic thin film transistors

Defect-Free Copolymer Gate Dielectrics for Gating MoS2 Transistors

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Product

Resources

About

Defect-Free Copolymer Gate Dielectrics for Gating MoS₂ Transistors