Low‐<i>k</i> Insulators as the Choice of Dielectrics in Organic Field‐Effect Transistors

Veres, János; Ogier, Simon; Leeming, Stephen; Cupertino, Domenico C.; Khaffaf, Soad Mohialdin

doi:10.1002/adfm.200390030

Cited by 750 publications

(638 citation statements)

References 22 publications

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“…Figure 4 shows the good fi t that was obtained for the PTrFE FET data using the model parameters obtained from the reference FET except that the conductivity prefactor σ 0 is lowered from 2 × 10 7 to 8.2 × 10 6 S m -1 . Such a reduction of a factor of two in the mobility closely corresponds to the decrease observed previously 24 for a dielectric constant increase from 4 to 10. Using the parameters from the PTrFE FET, the model predicts that the on-state drain current of 2 μA at zero gate bias in Fig.…”

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confidence: 87%

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High-performance solution-processed polymer ferroelectric field-effect transistors

et al. 2005

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We demonstrate a rewritable, non-volatile memory device with fl exible plastic active layers deposited from solution. The memory device is a ferroelectric fi eld-effect transistor (FeFET) made with a ferroelectric fl uoropolymer and a bisalkoxy-substituted poly(p-phenylene vinylene) semiconductor material. The on-and off-state drain currents differ by several orders of magnitude, and have a long retention time, a high programming cycle endurance and short programming time. The remanent semiconductor surface charge density in the on-state has a high value of 18 mC m -2 , which explains the large on/off ratio. Application of a moderate gate fi eld raises the surface charge to 26 mC m -2 , which is of a magnitude that is very diffi cult to obtain with conventional FETs because they are limited by dielectric breakdown of the gate insulator. In this way, the present ferroelectricsemiconductor interface extends the attainable fi eldeffect band bending in organic semiconductors.A memory element based on the ferroelectric fi eld-effect transistor (FeFET) is attractive because of its non-volatile data retention, small size, rewritability, non-destructive read-out, low-voltage operation and short programming time 1 . Its functionality arises from the attenuation of the charge carrier concentration in the semiconductor by the ferroelectric polarization of the gate insulator. Even though inorganic FeFETs have been studied for decades, a memory performance of any practical value has been achieved only in recent years [2][3][4][5][6][7][8] . The main problems that have arisen are charge trapping at the ferroelectric-semiconductor interface and the lack of thermal stability of the interface. This has prompted the use of insulating buffer layers between the semiconductor and ferroelectric to prevent charge injection and protect the semiconductor from the high-temperature annealing procedure that is required for inorganic ferroelectrics. Crucial device parameters for all memory devices are the on/ off ratio, data retention time, programming cycle endurance and programming time. Current state-of-the-art inorganic FeFETs have on/off ratios up to 10 9 , a retention time of 16 days and a programming time of 10 -8 s (refs 5,8). This is promising, although the high production cost of this non-CMOS (complementary metal-oxide-semiconductor) technology may hinder widespread application.Organic fi eld-effect transistors are ideally suited for low-cost, low-performance logic circuit applications on fl exible substrates 9 .

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confidence: 87%

“…3a. But such a direct comparison between this reference FET and the FeFET is not valid, because the charge carrier mobility in organic transistors decreases with increasing dielectric constant of the insulator 24 . The relative dielectric constant of the gate insulator of the reference FET is 3.4 whereas the measured value for P(VDF/TrFE) was 11.…”

mentioning

confidence: 99%

High-performance solution-processed polymer ferroelectric field-effect transistors

et al. 2005

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“…We do note that in the model of Tanase et al, the effect of dipolar disorder DOS broadening at the semiconductor-dielectric interface proposed by Veres et al [ 59 ] is not included. In this model static dipolar disorder in the dielectric increases the DOS width of the semiconductor in the FET channel.…”

Section: Resultsmentioning

confidence: 89%

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Campbell

Rawcliffe

Guite

et al. 2016

Adv Funct Materials

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3720 wileyonlinelibrary.com (OPVs), and organic fi eld-effect transistors (OFETs). A crucial parameter in the development of these technologies is the OSC charge-carrier mobility, and how it is related to the different OSC materials, processing, device architectures, and device operating conditions. Many semiconducting polymers and small molecules are amorphous, and such disorder in the physical morphology is expected to refl ect itself in disorder of the energy levels of the hole and electron transport states ( Figure 1 a). Such energetic disorder will directly impact charge transport and mobility. [1][2][3][4][5][6][7][8][9][10][11][12] For such energetically disordered OSCs, one feature predicted by many charge transport models is a charge-carrier density dependent mobility. The original Gaussian disorder model (GDM) developed by Bässler for hopping transport in a Gaussian density of states (DOS) distribution was a single carrier approach, [ 1 ] as were the models based on it which considered both correlated energetic disorder, [ 2 ] with a smoothly varying energy landscape (see Figure 1 a), and the effect of polaronic relaxation. [ 3 ] The percolation model developed by Vissenberg and Matters for transport involving an exponential DOS instead considered multiple carriers, [ 4 ] and this predicted a mobility which has a power-law dependency on the charge-carrier density. The measured transistor mobility falls two to three orders of magnitude below that predicted from the charge-carrier density dependent model, and does not follow the expected power-law relationship. The experimental results for these two amorphous polymers are therefore consistent with a charge-carrier density independent mobility, and this is discussed in terms of polaron-dominated hopping and interchain correlated disorder.

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“…For example, the phenomenon might be due to a variation in the gate dielectric constant of the film with the concentration of the PMMA solution. 17 Veres et al 2,18 suggested that a higher dielectric constant induces a broadening of the density of states ͑DOS͒ at the polymer/insulator interface. This results in a decrease in the DOS at the Fermi energy and subsequently causes a lower hopping probability, leading to a suppression of the carrier mobility.…”

Section: -2mentioning

confidence: 99%

Pentacene thin film transistors with a poly(methyl methacrylate) gate dielectric: Optimization of device performance

Yun¹,

Pearson²,

Petty³

2009

Journal of Applied Physics

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. The electrical characteristics of pentacene-based organic thin film transistors ͑OTFTs͒ using poly͑methyl methacrylate͒ ͑PMMA͒ as the gate dielectric are reported. Uniform pinhole-free and crack-free films of PMMA could be obtained by spin coating, with a lower limit of thickness of about 150 nm. The effects of the insulator thickness and channel dimensions on the performance of the devices have been investigated. Leakage currents, which are present in many polymeric gate dielectrics, were reduced by patterning the pentacene active layer. The resulting devices exhibited minimal hysteresis in their output and transfer characteristics. Optimized OTFT structures possessed a field-effect mobility of 0.33 cm 2 V −1 s −1 , a threshold voltage of Ϫ4 V, a subthreshold slope of 1.5 V/decade, and an on/off current ratio of 1.2ϫ 10 6 .

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Low‐k Insulators as the Choice of Dielectrics in Organic Field‐Effect Transistors

Cited by 750 publications

References 22 publications

High-performance solution-processed polymer ferroelectric field-effect transistors

High-performance solution-processed polymer ferroelectric field-effect transistors

Charge‐Carrier Density Independent Mobility in Amorphous Fluorene‐Triarylamine Copolymers

Pentacene thin film transistors with a poly(methyl methacrylate) gate dielectric: Optimization of device performance

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