High-electric-field transport in<i>a</i>-Si:H. II. Dark conductivity

Ce, Nebel; Ra, Street; Nm, Johnson; Cc, Tsai

doi:10.1103/physrevb.46.6803

Cited by 41 publications

(22 citation statements)

References 25 publications

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“…Thus, the theoretical prediction for the non-linear definition of the effective temperature, Eq. (32), is in good agreement with the experimental results [45,46,48]. Remarkable that this agreement holds in a wide temperature range up to very low temperatures where the quantum effects begin to play an important role.…”

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confidence: 89%

Hyperbolic heat conduction, effective temperature, and third law for nonequilibrium systems with heat flux

Соболев

2018

Phys. Rev. E

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Some analogies between different nonequilibrium heat conduction models, particularly random walk, the discrete variable model, and the Boltzmann transport equation with the single relaxation time approximation, have been discussed. We show that, under an assumption of a finite value of the heat carrier velocity, these models lead to the hyperbolic heat conduction equation and the modified Fourier law with relaxation term. Corresponding effective temperature and entropy have been introduced and analyzed. It has been demonstrated that the effective temperature, defined as a geometric mean of the kinetic temperatures of the heat carriers moving in opposite directions, acts as a criterion for thermalization and is a nonlinear function of the kinetic temperature and heat flux. It is shown that, under highly nonequilibrium conditions when the heat flux tends to its maximum possible value, the effective temperature, heat capacity, and local entropy go to zero even at a nonzero equilibrium temperature. This provides a possible generalization of the third law to nonequilibrium situations. Analogies and differences between the proposed effective temperature and some other definitions of a temperature in nonequilibrium state, particularly for active systems, disordered semiconductors under electric field, and adiabatic gas flow, have been shown and discussed. Illustrative examples of the behavior of the effective temperature and entropy during nonequilibrium heat conduction in a monatomic gas and a strong shockwave have been analyzed.

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supporting

confidence: 89%

Hyperbolic heat conduction, effective temperature, and third law for nonequilibrium systems with heat flux

Соболев

2018

Phys. Rev. E

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“…It rather follows a F -1/3 dependence (consistent with the observed scaling exponent S = 2/3), rather similar to previous experimental results [4,[31][32][33].…”

supporting

confidence: 88%

“…In this dynamical equilibrium context, the asymptotic energy level (called Ε t in [4] and ε f in [30]) is defined here by a field-dependent demarcation energy E DL (T, F) in the band tail, corresponding to the balance between electronic energy loss (down hopping) and field-assisted energy gain. By analogy with the temperature-dependent transport energy E T (T) in the ohmic regime (Eq.…”

Section: Demarcation Energy For Hopping In a High Electric Fieldmentioning

confidence: 99%

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Scaling analysis of field‐enhanced bandtail hopping transport in amorphous carbon nitride

Godet¹,

Kleider²,

Gudovskikh³

2007

Physica Status Solidi (b)

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International audienceHopping transport within a bandtail distribution of localized electronic states has been investigated in amorphous carbon nitride (a-C1-xNx:H, x = 0.23) as a function of temperature T and electric field F. The conductivity σ follows Mott's law in the ohmic regime, i.e. ln (σohmic) varies linearly with T-1/4, while at higher field, a scaling law, ln (σ /σohmic) = φ [FS /T ] with S = 0.67 (±0.05), is found. Data are fully consistent with a field-enhanced bandtail hopping (FBTH) model in which the effective temperature concept describes the non-equilibrium occupation probability of tail states. A "filling rate" method, considering forward non-activated hopping transitions, is developed to analyze the high field regime of FBTH. For an exponential distribution with disorder energy E0, increasing F shifts the transport energy EDL towards shallower tail states, with a density of states N (EDL) ∼ (F)3 (E0)-4. In this model, FBTH is parametrized using ln σ (T, F) vs T-1/4 plots, which provide field-dependent apparent values of prefactor (ln σ00) and slope (T01/4). As F increases, both parameters strongly decrease. This behavior (observed in a-C1-xNx:H, x = 0.23, for F > 5 × 104 V cm-1) is a signature of band tail hopping transport. Our FBTH model predicts a minimum value equation image of σ00(F), which is indeed observed in a-C1-xNx:H (x = 0.23) for T < 70 K (equation image ≈ 10-6 S cm-1 at Fmin ≈ 3 × 105 V cm-1). Near Fmin, kT *eff = (1/kTeff - 1/E0)-1 is parametrized by kT *eff ∼ Fq. The value of q that best reproduces the experimental results, q = 0.7 ± 0.1, is consistent with the scaling exponent S = 0.67 and with the density of states parameters deduced from the Ohmic regime. Hence, this "filling rate" method applied to FBTH transport appears to be very useful to analyze the apparent prefactor σ00(F) and to derive the effective temperature Teff(T, F) which governs bandtail states occupation and FBTH conductivity

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“…In the following, we show that another length scale, namely the localization length α, can be decisive for the field dependence of carrier mobility, as well known for inorganic non-crystalline semiconductors, in which field-dependent mobility in the hopping regime has been in the focus of intensive experimental and theoretical research for decades. This interest was implied by observations of a strong nonlinearity in the field dependences of the dark conductivity [198,199], of the photoconductivity [200], and of the charge carrier drift mobility [198,201,202] at high electric fields. Shklovskii [79] has recognized that strong electric field plays for hopping conduction a role similar to that of temperature.…”

Section: Concept Of the Effective Temperaturementioning

confidence: 99%

Theoretical description of charge transport in disordered organic semiconductors

Baranovskiǐ

2014

Physica Status Solidi (b)

303

365

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Twenty years ago Heinz Bässler published in this journal the seminal review article on charge transport in disordered organic semiconductors [Phys. Status Solidi B 175, 15 (1993)], which has become one of the most popular references in this research field. Thanks to this paper, our understanding of charge transport in disordered organic materials has been essentially improved in the past two decades. New theoretical methods have been developed and new results on various phenomena related to charge transport in disordered organic materials have been obtained. The aim of the current review is to present these new theoretical methods and to highlight the most essential results obtained in their framework. While theoretical consideration in the article by Bässler was based on computer simulations, particular attention in the current review is given to the development of analytical theories. Dependences of charge carrier mobility and diffusivity on temperature, electric field, carrier concentration and on material and sample parameters are discussed in detail. Schematic behaviour of charge carriers within the Gaussian density of states (DOS)

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High-electric-field transport ina-Si:H. II. Dark conductivity

Cited by 41 publications

References 25 publications

Hyperbolic heat conduction, effective temperature, and third law for nonequilibrium systems with heat flux

Hyperbolic heat conduction, effective temperature, and third law for nonequilibrium systems with heat flux

Scaling analysis of field‐enhanced bandtail hopping transport in amorphous carbon nitride

Theoretical description of charge transport in disordered organic semiconductors

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