Polarization-induced transport in ferroelectric organic field-effect transistors

Laudari, Amrit; Guha, S.

doi:10.1063/1.4914415

Cited by 28 publications

(25 citation statements)

References 34 publications

(45 reference statements)

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“…Ferroelectric dielectrics, permitting access to nearly an order of magnitude range of dielectric constants with temperature as the tuning parameter, offer a neat platform to monitor the changes in interfacial transport in organic FETs as the polarization strength is tuned. Temperature-dependent transport studies from pentacene FETs using the ferroelectric copolymer poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) showed a suppressed hole mobility in the ferroelectric phase of the dielectric [21]; similar characteristics were also observed in poly hexyl-thiophene (P3HT)/PVDF-TrFE FETs [22].…”

Section: Introductionmentioning

confidence: 70%

“…We point out that other analytical methods yield more accurate values of trap densities [31]. With PVDF-TrFE, however, N trap is seen to be discontinuous at the transition temperature, which was shown in P3HT [22] and pentacene based FETs [21].…”

Section: Temperature Dependent Fet Characteristicsmentioning

confidence: 76%

“…Prior work on ferroelectric FETs have shown that charge transport is strongly influenced by polarization fluctuation [21]. In the presence of a ferroelectric dielectric, the two competing effects as a function of temperature are a suppression of the charge carrier mobility in the ferroelectric phase (as a result of the coupling of the carrier to the dielectric polarization of the gate insulator) and an activated hopping transport responsible for enhancing µ F ET .…”

Section: Temperature Dependent Fet Characteristicsmentioning

confidence: 99%

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Bandlike Transport in Ferroelectric-Based Organic Field-Effect Transistors

Laudari

Guha

2016

Phys. Rev. Applied

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The dielectric constant of polymer ferroelectric dielectrics may be tuned by changing the temperature, offering a platform for monitoring changes in interfacial transport with the polarization strength in organic field-effect transistors (FETs). Temperature dependent transport studies of FETs have been carried out from a solution-processed organic semiconductor, 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), using both ferroelectric and nonferroelectric gate insulators. Non-ferroelectric dielectric based TIPS-pentacene FETs show a clear activated transport in contrast to the ferroelectric dielectric polymer, poly(vinylidene fluoridetrifluoroethylene) (PVDF-TrFE), where a negative temperature coefficient of the mobility is observed in the ferroelectric temperature range. The current-voltage (I-V) characteristics from TIPSpentacene diodes signal a space-charge-limited conduction (SCLC) for a discrete set of trap levels, suggesting that charge injection and transport occurs through regions of ordering in the semiconductor. The carrier mobility extracted from temperature-dependent I-V characteristics from the trap-free SCLC region shows a negative coefficient beyond 200 K, similar to the trend observed in FETs with the ferroelectric dielectric. At moderate temperatures, the polarization fluctuation dominant transport inherent to a ferroelectric dielectric in conjunction with the nature of traps results in an effective de-trapping of the shallow trap states into more mobile states in TIPS-pentacene.

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Section: Introductionmentioning

confidence: 70%

Section: Temperature Dependent Fet Characteristicsmentioning

confidence: 76%

Section: Temperature Dependent Fet Characteristicsmentioning

confidence: 99%

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Bandlike Transport in Ferroelectric-Based Organic Field-Effect Transistors

Laudari

Guha

2016

Phys. Rev. Applied

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“…PVDF‐based dielectrics have provided a platform to study transport properties as a function of the dielectric constant; κ of PVDF‐TrFE increases by a factor of 5 from its ferroelectric phase at 200 K to the paraelectric transition temperature at 390 K . Temperature‐dependent transport properties from small molecule and polymeric FETs with PVDF‐TrFE as the dielectric layer highlight polarization fluctuation transport; in particular, such studies reveal the nature of Fröhlich polarons in pentacene FETs …”

mentioning

confidence: 99%

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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“…[9][10][11] However, charge injection is surprisingly seldom studied in Fe-OFETs, although they have received intensive attention for various non-volatile memory device applications. [12][13][14][15] Few studies have been conducted because Fe-OFETs have long been suffering from low charge carrier mobility. Such a limiting factor has been recently overcome by our interfacial buffering method, which inserts an ultrathin poly(methyl methacrylate) (PMMA) between the ferroelectric gate insulator and organic semiconductor layers.…”

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confidence: 99%

Reducing contact resistance in ferroelectric organic transistors by buffering the semiconductor/dielectric interface

Sun

Yin

Wang

et al. 2015

Applied Physics Letters

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The reduction of contact resistance in ferroelectric organic field-effect transistors (Fe-OFETs) by buffering the interfacial polarization fluctuation was reported. An ultrathin poly(methyl methacrylate) layer was inserted between the ferroelectric polymer and organic semiconductor layers. The contact resistance was significantly reduced to 55 kΩ cm. By contrast, Fe-OFETs without buffering exhibited a significantly larger contact resistance of 260 kΩ cm. Results showed that such an enhanced charge injection was attributed to the buffering effect at the semiconductor/ferroelectric interface, which narrowed the trap distribution of the organic semiconductor in the contact region. The presented work provided an efficient method of lowering the contact resistance in Fe-OFETs, which is beneficial for the further development of Fe-OFETs.

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Polarization-induced transport in ferroelectric organic field-effect transistors

Cited by 28 publications

References 34 publications

Bandlike Transport in Ferroelectric-Based Organic Field-Effect Transistors

Bandlike Transport in Ferroelectric-Based Organic Field-Effect Transistors

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

Reducing contact resistance in ferroelectric organic transistors by buffering the semiconductor/dielectric interface

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