Steady-state hopping conduction in the conduction-band tail of<i>a</i>-Si:H studied in thin-film transistors

Nagy, A.; Hundhausen, Martin; Ley, L.; Brunst, G.; Holzenkämpfer, E.

doi:10.1103/physrevb.52.11289

Cited by 12 publications

(7 citation statements)

References 15 publications

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“…In an attempt to elucidate the distribution in energy of the density of states (DOS) N(E ) and of the localization length À1 (E ) in amorphous semiconductors, high-electric-field transport has been extensively studied, particularly in films of amorphous germanium (Elliott et al 1974, Eray et al 1990), hydrogenated amorphous silicon (a-Si : H) (Stachowitz et al 1990, Nebel et al 1992a, b, Devlen et al 1993, Palsule et al 1994, Nagy et al 1995, Gu et al 1996 and hydrogenated amorphous carbon (Hastas et al 2002, Godet et al 2003. Strong nonlinearities in the field dependence of the dark conductivity, of the photoconductivity and of the carrier drift mobility have been observed in a temperature range where hopping transport unambiguously occurs.…”

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confidence: 99%

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Analytical derivation of the effective temperature for field-dependent hopping conductivity

Godet

2003

Philosophical Magazine Letters

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The electric-field enhancement of hopping conductivity in amorphous solids can be described in terms of an effective temperature T eff given by T 2 eff % T 2 þ ½CðFÞ À1 eF=k 2 for hopping, at a temperature T and field F, within a uniform distribution of electronic states with localization length À1 . We have derived this expression analytically and find at low fields a value for C of 1/2 1/2 , which is consistent with the F-independent value C ¼ 0.67 previously obtained numerically for band-tail hopping. With increasing electric field, the decrease in C(F) matches the hopping transport characteristics in amorphous semiconductors (hydrogenated amorphous silicon and hydrogenated amorphous carbon nitride) better than previous numerical simulations.

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confidence: 99%

“…Similarly, high-field hopping transport has been modelled using (i) percolation theory (Pollak and Riess 1976, Van der Meer et al 1982), (ii) Monte Carlo simulations (Cleve et al 1995) and (iii) an energy-and field-dependent hopping mobility (E, F ) (Apsley and Hughes 1975, Nebel and Street 1993, Nagy et al 1995, Hundhausen et al 1996.…”

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confidence: 99%

Analytical derivation of the effective temperature for field-dependent hopping conductivity

Godet

2003

Philosophical Magazine Letters

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“…This latter is actually the present case, where TSCs with a high initial carrier density measured in a wide temperature range are considered. In order to go beyond the TE approach several alternatives have been considered, but some degree of approximation is always needed if we want to get expressions useful for fitting purposes; to this aim we have used the approach already proposed by Nagy that offer a maximum of simplicity. The average hopping distance r ( E ) for a site of energy E is defined as

\frac{1}{R_{normalL}^{3}} = \frac{4}{3} π N_{normalL} = \frac{4}{3} π \int_{- \infty}^{0} g false(E false) normald E,

\frac{1}{r {(E)}^{3}} = \frac{1}{B R_{normalL}^{3}} \int_{- \infty}^{E} g false(E' false) ((), 1 - f false(E', E_{F}, T false)) normald E',

with R L average distance between localized states.…”

Section: Discussionmentioning

confidence: 99%

“…The average hopping distance r ( E ) for a site of energy E is defined as

\frac{1}{R_{normalL}^{3}} = \frac{4}{3} π N_{normalL} = \frac{4}{3} π \int_{- \infty}^{0} g false(E false) normald E,

\frac{1}{r {(E)}^{3}} = \frac{1}{B R_{normalL}^{3}} \int_{- \infty}^{E} g false(E' false) ((), 1 - f false(E', E_{F}, T false)) normald E',

with R L average distance between localized states. The constant B = 2.7 is introduced to take into account of the percolation nature of the hopping transport . The function r ( E ) = r ( E , E F , T ), defined by Eq.…”

Section: Discussionmentioning

confidence: 99%

Low temperature thermally stimulated current characterization of nanoporous TiO₂ films

Bruzzi

Mori

Carnevale

et al. 2014

Phys. Status Solidi A

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Nanoporous films of TiO 2 have been obtained by deposition on an alumina substrate of a commercial colloid and Au contacts have been put on surface for in-plane conductivity measurements. Samples have been characterized by means of a series of sequential thermally stimulated currents scans, from nearly liquid He temperature up to 200 K, in order to get information on: conduction mechanisms, distribution of intragap density of states and recombination times of free an localized carriers.A model for hopping conductivity has been considered to properly take into account of localized states filling; it has been used to fit the experimental data, without a-priori assumptions on the nature of the conduction mechanisms. It is found that hopping conductivity prevails over free-carrier, in quasi-equilibrium regime, in the investigated temperature range.

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“…The net hopping conductivity can be calculated by the integration of the differential sheet conductivity of each states contributing to the conduction [52]. Furthermore, the differential sheet conductivity is a complicated function of the distribution of localized states.…”

Section: Simulationsmentioning

confidence: 99%

A field-effect approach to directly profiling the localized states in monolayer MoS2

Liu

Deng

et al. 2019

Science Bulletin

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A fundamental understanding of the charge transport mechanism in two-dimensional semiconductors (e.g., MoS 2) is crucial for fully exploring their potential in electronic and optoelectronic devices. By using monolayer graphene as the barrier-free contact to MoS 2 , we show that the field-modulated conductivity can be used to probe the electronic structure of the localized states. A series of regularly distributed plateaus were observed in the gate-dependent transfer curves. Calculations based on the variable-range hopping theory indicate that such plateaus can be attributed to the discrete localized states near mobility edge. This method provides an effective approach to directly profiling the localized states in conduction channel with an ultrahigh resolution up to 1 meV.

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Steady-state hopping conduction in the conduction-band tail ofa-Si:H studied in thin-film transistors

Cited by 12 publications

References 15 publications

Analytical derivation of the effective temperature for field-dependent hopping conductivity

Analytical derivation of the effective temperature for field-dependent hopping conductivity

Low temperature thermally stimulated current characterization of nanoporous TiO₂ films

A field-effect approach to directly profiling the localized states in monolayer MoS2

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Steady-state hopping conduction in the conduction-band tail ofa-Si:H studied in thin-film transistors

Cited by 12 publications

References 15 publications

Analytical derivation of the effective temperature for field-dependent hopping conductivity

Analytical derivation of the effective temperature for field-dependent hopping conductivity

Low temperature thermally stimulated current characterization of nanoporous TiO2 films

A field-effect approach to directly profiling the localized states in monolayer MoS2

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Product

Resources

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Low temperature thermally stimulated current characterization of nanoporous TiO₂ films