Hopping Conductivity in Granular Metals

Sheng, Ping; Abeles, B.; Arie, Y.

doi:10.1103/physrevlett.31.44

Cited by 904 publications

(498 citation statements)

References 12 publications

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“…In conventional ES VRH, Coulomb interaction effects lead to a soft-gapped density of states around E F giving r ¼ r ES exp (T ES /T) 1/2 , where T ES ¼ 2.8 e 2 /kk B L C , and k is the dielectric constant 29 . A similar T dependence can, however, also be obtained from thermally assisted tunnelling between nanoscopic conductive regions in a more insulating matrix, due to the Coulomb penalty associated with single carrier charging 30 . Such models have been adapted to semiconducting polymers 8 and claims of observation of this mechanism have been made 9 .…”

Section: Electrochemical Thin Film Transistorsmentioning

confidence: 82%

“…28). The T À 1/2 behaviour, however, could be interpreted in a number of ways, particularly conventional Efros-Shklovskii (ES) VRH 29 or inter-cluster hopping 30 . In conventional ES VRH, Coulomb interaction effects lead to a soft-gapped density of states around E F giving r ¼ r ES exp (T ES /T) 1/2 , where T ES ¼ 2.8 e 2 /kk B L C , and k is the dielectric constant 29 .…”

Section: Electrochemical Thin Film Transistorsmentioning

confidence: 99%

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Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

et al. 2012

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Despite 35 years of investigation, much remains to be understood regarding charge transport in semiconducting polymers, including the ultimate limits on their conductivity. Recently developed ion gel gating techniques provide a unique opportunity to study such issues at very high charge carrier density. Here we have probed the benchmark polymer semiconductor poly(3-hexylthiophene) at electrochemically induced three-dimensional hole densities approaching 10 21 cm À 3 (up to 0.2 holes per monomer). Analysis of the hopping conduction reveals a remarkable phenomenon where wavefunction delocalization and Coulomb gap collapse are disrupted by doping-induced disorder, suppressing the insulator-metal transition, even at these extreme charge densities. Nevertheless, at the highest dopings, we observe, for the first time in a polymer transistor, a clear Hall effect with the expected field, temperature and gate voltage dependencies. The data indicate that at such mobilities (B0.8 cm 2 V À 1 s À 1 ), despite the extensive disorder, these polymers lie close to a regime of truly diffusive band-like transport.

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Section: Electrochemical Thin Film Transistorsmentioning

confidence: 82%

Section: Electrochemical Thin Film Transistorsmentioning

confidence: 99%

Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

et al. 2012

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“…9͒, showing the expected behavior for thermally assisted tunneling in the dielectric regime. 4,5,7,11,12 In contrast, C p is almost temperature inde- …”

Section: Random R-c Networkmentioning

confidence: 99%

“…The dc conductance was extrapolated from measurements at 12 Hz. The temperature dependence of the dc resistivity ͑T͒ in the dielectric regime can be satisfactorily described by thermally assisted tunneling and Coulomb blockade for all samples and follows the expression ͑T͒ ϳ exp͑2 ͱ B / k B T͒, 4,5,7 where the parameter B shows strong dependence with Co content ͑see below͒. B is directly related to the Coulomb charging energy of the particles E C 0 , as B = E C 0 d , being d the interparticle distance and as the tunneling barrier height in momentum units.…”

Section: Transport Propertiesmentioning

confidence: 99%

“…When particles are reduced to nanometer sizes, their properties differ considerably from the corresponding bulk counterpart, giving rise to new phenomena which result from finite-size, surface, and proximity effects, and interparticle interactions, leading to a variety of enhanced properties. [2][3][4][5][6][7][8][9][10][11][12] While dc transport properties of insulating granular thin films have been widely studied since 1970s, 4,5,7-10 much less attention has been paid to the ac response of these systems, for which many effects are not yet completely understood. In particular, we recently showed that the ac electrical properties of Co nanoparticles embedded into a dielectric ZrO 2 matrix display a complex lowfrequency absorption phenomenon 11,12 in the dielectric regime below the percolation threshold for Co that mimics the so-called universal response 13 of disordered dielectric materials, which remains a topic of very active experimental and theoretical researches.…”

Section: Introductionmentioning

confidence: 99%

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ac conductance in granular insulatingCo-ZrO2thin films: A universal response

et al. 2009

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The ac conductance in granular insulating Co-ZrO 2 thin films prepared by pulsed laser deposition is systematically studied as a function of the Co volume content x. An absorption phenomenon at low frequencies that mimics the universal response of disordered dielectric materials is observed in the range of metal content below the Co percolation threshold x p Ϸ 0.35 in the so-called dielectric regime. The temperature and frequency dependences of this absorption phenomenon are successfully analyzed in terms of random competing conduction channels between Co particles through thermally assisted tunneling and capacitive conductance. The ac conductance is well correlated with the nanostructure of the samples obtained by the transmission electron microscopy and perfectly matches the calculated ac response for a random resistor-capacitor network. We also show the occurrence of fractional power-law dependences on the frequency of the ac conductance taking place at very low frequencies as compared to the typical ranges at which dispersive behavior is observed in classicaldisordered dielectric materials.

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Interplay of Hopping and Percolation in Organic Conducting Blends

Fraysse

Planès

2000

phys. stat. sol. (b)

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Electronic transport properties of organic conductive blends made of doped poly(aniline) and poly(methyl methacrylate) are studied as a function of the conductive phase fraction p and the temperature T. As p is varied, the scaling law of electrical percolation, σ ∝ (p — pc)t, is obeyed by the dc conductivity σ with a single value of pc = 0.07% for a wide range of temperatures. Conversely, the conductivity exponent t increases monotonically from 1.4 to 4.3 as T decreases. At constant p, the thermal dependence of σ is described by the superposition of a metallic part and a hopping part. In the hopping law, ln σ ∝ —(T0/T)γ, the exponent is p dependent. Considering a wide and T dependent distribution of local conductances, we may explain the non‐canonical behavior of exponents t (continuous percolation model) and γ.

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Hopping Conductivity in Granular Metals

Abstract: The data points in Fig. 2

Cited by 904 publications

References 12 publications

Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

Hopping transport and the Hall effect near the insulator–metal transition in electrochemically gated poly(3-hexylthiophene) transistors

ac conductance in granular insulatingCo-ZrO2thin films: A universal response

Interplay of Hopping and Percolation in Organic Conducting Blends

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