Polarization fluctuation dominated electrical transport processes of polymer-based ferroelectric field effect transistors

Senanayak, Satyaprasad P.; Guha, S.; Narayan, K. S.

doi:10.1103/physrevb.85.115311

Cited by 42 publications

(62 citation statements)

References 37 publications

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“…As seen in Ref. 20, the ferroelectric environment in PVDF-based copolymers has a strong contribution to polarization fluctuation driven transport (which is reflected in the strong T-dependence of j) compared to the static dipolar induced disorder observed in non-polar dielectrics.…”

Section: Introductionmentioning

confidence: 83%

“…26 Furthermore, the correction due to thermalization of individual dipoles (as a result of the nonlinear contribution) when the system approaches T c has not been taken into account here. 20 Taking this correction may slightly reduce the mobility in the ferroelectric phase, thus further enhancing D. Since the OFETs in this work are low operating voltage devices, the nonlinear contribution may not be that high as evident from a prior work on polarization measurements from PVDF-TrFE capacitors with similar thicknesses. 23 The trend in Fig.…”

Section: B Thickness-dependence Of the Ferroelectric Layermentioning

confidence: 92%

“…The dielectric constant of PVDF-TrFE as a function of temperature is also plotted. 20 The discontinuity at 390 K denotes the ferroelectric to the paraelectric phase. The suppression of the charge carrier mobility with increasing temperature in the ferroelectric phase may be attributed to a coupling of the charge carriers to the dielectric polarization of the gate insulator, resulting in a renormalization of the transfer integral, J.…”

Section: A Comparison Of Polar Versus Non-polar Dielectricmentioning

confidence: 99%

“…A recent work by Senanayak et al shows that copolymers of PVDF permit an order of magnitude change in the polarization with temperature. 20 In particular, j changes from 4 to 24 in PVDF-TrFE when the temperature is varied from 200 K to the ferroelectric-paraelectric phase transition at 390 K (T c ). By using the same organic semiconductor-insulator interface, PVDF-TrFE allows a platform for understanding transport as the polarization strength is tuned from a weak-to strong-coupling regime with changing temperature (T).…”

Section: Introductionmentioning

confidence: 99%

“…20 In this work, we employ pentacene as the organic semiconductor, mainly, so that we can compare our experimental results with theory as well as compare the temperature dependent transport characteristics of pentacene OFETs with other non-polar dielectrics, as discussed in Sec. III A.…”

Section: Introductionmentioning

confidence: 99%

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Polarization-induced transport in ferroelectric organic field-effect transistors

Laudari

Guha

2015

Journal of Applied Physics

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Articles you may be interested inLow-voltage organic field-effect transistors based on novel high-κ organometallic lanthanide complex for gate insulating materials AIP Advances 4, 087140 (2014); 10.1063/1.4894450Enhanced performance of ferroelectric-based all organic capacitors and transistors through choice of solvent Appl. Phys. Lett.Surface modification of a ferroelectric polymer insulator for low-voltage readable nonvolatile memory in an organic field-effect transistor Ferroelectric dielectrics, permitting access to nearly an order of magnitude range of dielectric constants with temperature as the tuning parameter, offer a great platform to monitor the changes in interfacial transport in organic field-effect transistors (OFETs) as the polarization strength is tuned. Temperature-dependent transport studies have been carried out from pentacene-based OFETs using the ferroelectric copolymer poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) as a gate insulating layer. The thickness of the gate dielectric was varied from 20 nm to 500 nm. By fits to an Arrhenius-type dependence of the charge carrier mobility as a function of temperature, the activation energy in the ferroelectric phase is found to increase as the thickness of the PVDF-TrFE layer decreases. The weak temperature-dependence of the charge carrier mobility in the ferroelectric phase of PVDF-TrFE may be attributed to a polarization fluctuation driven transport, which results from a coupling of the charge carriers to the surface phonons of the dielectric. By comparing single layer PVDF-TrFE pentacene OFETs with stacked PVDF-TrFE/inorganic dielectric OFETs, the contribution from Fr€ ohlich polarons is extracted. The temperature-dependent mobility of the polarons increases with the thickness of the PVDF-TrFE layer. Using a strongly coupled polaron model, the hopping lengths were determined to vary between 2 Å and 5 Å . V C 2015 AIP Publishing LLC. [http://dx.

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Section: Introductionmentioning

confidence: 83%

Section: B Thickness-dependence Of the Ferroelectric Layermentioning

confidence: 92%

Section: A Comparison Of Polar Versus Non-polar Dielectricmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polarization-induced transport in ferroelectric organic field-effect transistors

Laudari

Guha

2015

Journal of Applied Physics

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Strategies for Fast‐Switching in All‐Polymer Field Effect Transistors

Senanayak

Narayan

2014

Adv Funct Materials

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3324www.MaterialsViews.com wileyonlinelibrary.com dielectric layer ( t dielectric ) and disorder at the semiconductor-dielectric interface ( t interface ). Understanding different sources of contribution to the switching process in PFETs should enable design of high gain-bandwidth organic-circuits. In this regard, we present a comprehensive set of studies using a variety of dielectric and semiconducting layers, to arrive at a working model for the FET-dynamics. We address the limiting factors for switching and implement a strategy which enables in realizing three orders of magnitude enhancement in the response-time of these polymer devices. The highlight of this approach is that it is particularly suited for channel length regimes which come under the realm of low-cost printing methods and can be universally extended for different classes of disordered FE.The electrical transport in PFETs is controlled by energetic-disorder and dielectric fl uctuations which generally result in broadening of density of states ( E broad ). It was recently observed that some of these issues can be mitigated with the use of polar FE dielectric. [ 9,10 ] FE dielectrics are known to form structural and energetically ordered interface with activation energy ( E A ) ≈ 14 meV. [ 9 ] Additionally, FE layer in PFETs enable large transverse fi elds at low gate voltage ( V g ) in order to observe the pinch-off (at lower V ds ). [ 3,11,12 ] This aspect is signifi cant in the case of PFETs where lowering channel-length to short-channel regime introduces large deviation from ideal long-channel saturation behavior. It is generally accepted that channel length needs to be about four times the dielectric thickness to observe saturation behavior. [ 8 ] Microscopically ordered interface and high transverse fi eld using a FE dielectric assists in improving the static and dynamic performance of PFETs. The large polarization in FE is also associated with slow response to an external time varying electric fi eld. [ 13,14 ] This slow component of the bulk FE relaxation limits the switching response ( t switch ≈ t dielectric ) of FE-FET, hence the fastest response obtained till-date is 0.3 ms. [ 15 ] In order to overcome this limitation, we demonstrate that poling (electric-fi eld induced orientation) the transport interface near ferroelectric transition temperature ( T c ≈ 390 K) overcomes the slow relaxation, thereby enhancing the frequency response (ca. three orders of magnitude). Poling of FE layer is known to modify the relaxation process and the relaxation time decreases with higher magnitude of applied fi eld. [ 16 ] This large enhancement is attributed to the fast domain nucleation process in Low-cost printable fi eld effect transistors (FETs) are typically associated with slow switching characteristics. Dynamic response of polymer fi eld effect transistors (PFETs) is a manifestation of time scales involved in processes such as dielectric polarization, structural relaxation, and transport via disorderedinterfacial states. A range of dielectrics an...

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Textured Poling of the Ferroelectric Dielectric Layer for Improved Organic Field‐Effect Transistors

Laudari

Pickett

Hogan

et al. 2019

Adv Materials Inter

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the amorphous silicon benchmark of 1 cm 2 Vs −1 , application of organic FETs in displays and sensors have now become a reality. Organic FETs differ from metal oxide semiconductor FET (MOSFET) in several ways; most organic FETs operate in the accumulation region compared to the inversion operating region of MOSFETs. The metal-semiconductor and the semiconductor-dielectric interfaces play a vital role in charge transport properties. In particular, the dielectric interface is notorious for charge trapping. As a result, achieving intrinsic transport in the organic semiconductor layer in FET architectures is very challenging. Using the same organic semiconductor film (either evaporated or solution processed) but different dielectric layers may yield order of magnitude differences in FET carrier mobilities. On the other hand, ultrapure organic single crystals such as rubrene, grown from vapor phase, have shown intrinsic FET mobilities higher than 20 cm 2 Vs −1 . [2] Since the charge accumulation is directly proportional to the dielectric capacitance (C), where; κ being the dielectric constant, ε 0 the permittivity of free space, A the area of the capacitor, and d the thickness of the dielectric, a high value of the dielectric capacitance is required for lowering the operating voltage of FETs. Low-operating voltage FETs, therefore, demand high κ dielectrics, which are more difficult to achieve with polymeric materials compared to inorganic dielectric materials due to their inherently low κ values. Facile methods of preparing polymer dielectrics by appropriate choice of solvents result in thin (well below 100 nm) and pinhole-free films for low-operating voltage FETs. [3,4] Polymer ferroelectrics with higher values of κ compared to non-ferroelectric polymers allow an alternate route toward boosting the capacitance values in FETs. Poly(vinylidene fluoride) (PVDF) ferroelectric polymer and its copolymer such as PVDF trifluorethylene (PVDF-TrFE) with κ > 8 at room temperature have been extensively used in memory and pressure sensing applications. [5][6][7][8][9] Naturally, such dielectrics also provide a route toward low-operating voltage FETs. The vast range of work has utilized PVDF and its copolymers as a gate dielectric in organic FETs. [10][11][12][13] Design of PVDF with carbon quantum dots has opened applications in nanogenerators where the mechanical energy may be efficiently converted to electricity. [14] More recently, PVDF copolymers have been used with charge-modulated organic FETs for multimodal Polymer ferroelectrics are playing an increasingly active role in flexible memory application and wearable electronics. The relaxor ferroelectric dielectric, poly(vinylidene fluoride trifluorethylene (PVDF-TrFE), although vastly used in organic field-effect transistors (FETs), has issues with gate leakage current especially when the film thickness is below 500 nm. This work demonstrates a novel method of selective poling the dielectric layer. By using solutionprocessed 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-p...

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Polarization fluctuation dominated electrical transport processes of polymer-based ferroelectric field effect transistors

Abstract: Abstract

Cited by 42 publications

References 37 publications

Polarization-induced transport in ferroelectric organic field-effect transistors

Polarization-induced transport in ferroelectric organic field-effect transistors

Strategies for Fast‐Switching in All‐Polymer Field Effect Transistors

Textured Poling of the Ferroelectric Dielectric Layer for Improved Organic Field‐Effect Transistors

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