Meyer Neldel Research Articles

Introducing effective temperature into Arrhenius equation with Meyer-Neldel rule for describing both Arrhenius and non-Arrhenius dependent drain current of amorphous InGaZnO TFTs

The drain current of the amorphous InGaZnO thin-film transistors (TFTs) shows the Arrhenius and the non-Arrhenius dependence at the high temperature and the low temperature respectively. The gate-voltage-dependent effective temperature is introduced into the Arrhenius equation. Considering the normal Meyer-Neldel (MN) rule and the inverse MN rule, the equation successfully describes both the Arrhenius and the non-Arrhenius dependent drain current at the low and the high gate voltage. The calculated results of the equation are verified by the available experimental data of the amorphous La-doped InZnO TFT and the amorphous InGaZnO (InO3:Ga2O3:ZnO = 1:1:1 mol%) TFT.

Investigating the cross-slip rate in face-centered cubic metals using an atomistic-based cross-slip model in dislocation dynamics simulations

The cross-slip rate of screw segments in dislocation dynamics simulations was calculated using the model of Esteban-Manzanares et al. (2020), which is based on a combination of the harmonic transition state theory and the Meyer–Neldel rule. In said model, the cross-slip rate is expressed as a function of the microstructure parameters. In particular, the rate prefactor depends on the nucleation length of cross-slip and the activation enthalpy, which are themselves functions of the local stress. Malka-Markovitz and Mordehai (2019) solved the line tension model of cross-slip exactly by linearizing the interaction force between the partials. They obtained analytical expressions for the nucleation length and the activation enthalpy as functions of a general stress state. These expressions were used to evaluate the cross-slip rate at each simulation step. The results are in quantitative agreement with atomistic simulations.

The Basic Theorem of Temperature-Dependent Processes

The basic theorem of isokinetic relationships is formulated as “if there exists a linear correlation “structure∼properties” at two temperatures, the point of their intersection will be a common point for the same correlation at other temperatures, until the Arrhenius law is violated”. The theorem is valid in various regions of thermally activated processes, in which only one parameter changes. A detailed examination of the consequences of this theorem showed that it is easy to formulate a number of empirical regularities known as the “kinetic compensation effect”, the well-known formula of the Meyer–Neldel rule, or the so-called concept of “multi-excitation entropy”. In a series of similar processes, we examined the effect of different variable parameters of the process on the free energy of activation, and we discuss possible applications.

Rethinking the Design of Ionic Conductors Using Meyer–Neldel–Conductivity Plot

AbstractFrom the discovery of the first fast ionic conductor silver iodide in the early 20th century to the recent discovery of lithium fast ionic conductors with ionic conductivities surpassing those of liquid electrolytes, high ionic conductivity σ has often been associated with low activation energy Ea following the Arrhenius equation. However, the Meyer–Neldel rule (MNR) indicates that the Ea and prefactor σ0 are correlated, suggesting the relation between the Ea and σ is, in fact, complex. In this perspective, the use of the Meyer–Neldel–conductivity plot and a critical descriptor, Meyer–Neldel energy Δ0, to guide the search for fast ionic conductors is proposed. Reported lithium, sodium, and magnesium ionic conductors are categorized into three types, depending on the relative magnitude between the Δ0 and thermal energy (kBT) at the application temperature. The process by which σ can be optimized by tuning Ea for these types of ionic conductors is elaborated. This principle can be widely applied to all ionic conductors that obey the MNR at any application temperature. Furthermore, a pressure‐tuning approach to measure the Δ0 rapidly is developed. These findings establish a previously missing step for designing new ionic conductors with improved ionic conductivity.

Reverse Meyer-Neldel rule prevailing in the hole transport of B-doped nc-SiOx:H thin films sustaining degeneracy and performing as suitable window of nc-Si solar cells

Low-temperature (~250 °C) plasma-CVD grown heavily B-doped nc-Si:H film with ~73% crystallinity, high electrical conductivity ~2.0 S cm−1, corresponding to elevated carrier (hole) density ~2.4 × 1019 cm−3, appears as a degenerate-like semiconductor. On oxygen incorporation into the network, the hole transport in p–nc-SiOx:H films follows thermally activated electrical conduction, with single activation energy. The prime achievement remains in sustaining the degeneracy up to certain level of O-incorporation into the doped nc-Si:H network retaining gradually reduced crystallinity, decreased electrical conductivity and widened optical band gap, Eg. While sustaining degeneracy, the p–nc-SiOx:H film follows the reverse Meyer–Neldel Rule (MNR) in the hole transport phenomena, revealing negative sign in the Meyer-Neldel characteristic energy, EMN < 0. However, further increased oxygen inclusion corresponding to a transition of the network from Si-rich nc-SiOx:H phase to O-rich and amorphous dominated SiOx:H phase with corresponding carrier density nh < 1017 cm−3, consequences a switching in the hole transport characteristics to the conventional MNR type with positive characteristic energy, EMN > 0, and conversion to the non-degenerate configuration. Such a transition in degeneracy in nano-hetero-structured doped Si–H–O complex network has never been demonstrated earlier. The p–nc-SiOx:H film, optimized in the degenerate zone emerges as suitable window layer of the single-junction laboratory-scale nc-Si solar cells.

Probing the ionic defect landscape in halide perovskite solar cells

Point defects in metal halide perovskites play a critical role in determining their properties and optoelectronic performance; however, many open questions remain unanswered. In this work, we apply impedance spectroscopy and deep-level transient spectroscopy to characterize the ionic defect landscape in methylammonium lead triiodide (MAPbI3) perovskites in which defects were purposely introduced by fractionally changing the precursor stoichiometry. Our results highlight the profound influence of defects on the electronic landscape, exemplified by their impact on the device built-in potential, and consequently, the open-circuit voltage. Even low ion densities can have an impact on the electronic landscape when both cations and anions are considered as mobile. Moreover, we find that all measured ionic defects fulfil the Meyer–Neldel rule with a characteristic energy connected to the underlying ion hopping process. These findings support a general categorization of defects in halide perovskite compounds.

Investigation of the Meyer-Neldel Rule in Si MOSFETs

We show that a Meyer-Neldel (MN) regime, usually reported for disordered materials, is found in state-of-the-art monocrystalline Si MOSFETs. This unexpected result is explained via device simulation in terms of the self-consistency between the mobile charge and the device electrostatics. The dependence on device parameters is then discussed, showing that neglecting this effect can lead to interpretation errors for data evaluated at low activation energies.

Anomalies in Bulk Ion Transport in the Solid Solutions of Li7La3M2O12 (M = Hf, Sn) and Li5La3Ta2O12.

Cubic Li7La3Zr2O12(LLZO), stabilized by supervalent cations, is one of the most promising oxide electrolyte to realize inherently safe all-solid-state batteries. It is of great interest to evaluate the strategy of supervalent stabilization in similar compounds and to describe its effect on ionic bulk conductivity σ′bulk. Here, we synthesized solid solutions of Li7–xLa3M2–xTaxO12 with M = Hf, Sn over the full compositional range (x = 0, 0.25...2). It turned out that Ta contents at x of 0.25 (M = Hf, LLHTO) and 0.5 (M = Sn, LLSTO) are necessary to yield phase pure cubic Li7–xLa3M2–xTaxO12. The maximum in total conductivity for LLHTO (2 × 10–4 S cm–1) is achieved for x = 1.0; the associated activation energy is 0.46 eV. At x = 0.5 and x = 1.0, we observe two conductivity anomalies that are qualitatively in agreement with the rule of Meyer and Neldel. For LLSTO, at x = 0.75 the conductivity σ′bulk turned out to be 7.94 × 10–5 S cm–1 (0.46 eV); the almost monotonic decrease of ion bulk conductivity from x = 0.75 to x = 2 in this series is in line with Meyer–Neldel’s compensation behavior showing that a decrease in Ea is accompanied by a decrease of the Arrhenius prefactor. Altogether, the system might serve as an attractive alternative to Al-stabilized (or Ga-stabilized) Li7La3Zr2O12 as LLHTO is also anticipated to be highly stable against Li metal.

The compensation effect (Meyer–Neldel rule) on [AlO4/h+] and [TiO4/M+] paramagnetic centers in irradiated sedimentary quartz

The effect of thermal excitation on paramagnetic defects in natural sedimentary quartz irradiated with different doses of gamma radiation was studied using electron spin resonance (ESR) spectroscopy. We report a variation in the activation energy and the frequency factor for [AlO4/h+]0 and [TiO4/M+]0 paramagnetic defects with the gamma dose, for a dose range investigated between ∼100 Gy and ∼40 000 Gy. Our results indicate that both [AlO4/h+]0 and [TiO4/M+]0 defects are less thermally stable above 1 kGy–2 kGy than below this dose range. The correlation between the two kinetic parameters (activation energy and frequency factor) satisfies the Meyer–Neldel rule. A linear correlation was found between the amplitude of the ESR signals of [AlO4/h+]0 and [TiO4/M+]0 paramagnetic defects corresponding to different doses after the application of thermal treatments in the pulse annealing procedure. We propose a mechanism involving the exchange of the cation, assigned mainly to Li+ here, between the two defects. Under irradiation, the cation is removed from [AlO4/M+]0 (forming [AlO4/h+]0) to [TiO4]− (forming [TiO4/M+]0), while under heating, the reverse mechanism takes place. The migration energy of the cation from one defect to another was found to be about 51 meV, corresponding to a temperature of about 325 °C.

Charge Carrier Transport in a Polymeric Semiconductor: Poly(3-hexylthiophene-2,5-diyl) (P3HT)

Organic semiconductors are now widely employed in electronic and optoelectronic devices due to their solution processability and compatibility with flexible substrates. 1 The Meyer Neldel (MN) Rule or isokinetic (IK) law means that a set of comparable samples exhibit kinetic behavior independent of activation energy at an IK or MN temperature.2 It is obeyed by the electron or hole mobility, µ, in many organic semiconductors, including pentacene3, fullerene4, N-Alkyl Perylene Diimides,5 etc. The existence of MNR is still not widely known. Further, despite considerable evidence in its favor, the multi-excitation entropy (MEE) model of its origin is still frequently contested. We fabricated organic field effect transistors (FETs) based on regioregular poly(3-hexylthiophene-2,5-diyl) (RR P3HT) of three different values of molecular weight, MW, and studied the dependence of the mobility, µ, upon the gate bias, Vg , and temperature, T. For all values of MW, we found that in the range 200 to 290 K (low T), the µ of the FET carriers exhibits an exponential dependence upon 1/T for different Vg , with an MN temperature about 290K. Between this temperature and 350K (high T), µ increases more rapidly than it did below, and is independent of Vg . We believe that, in the low T regime, the polaronic carriers hop along the polymer backbone chain. We attribute the high temperature behavior to the alpha relaxation of the polymers, that is to the movement of the backbone chains. We believe that in this regime, the polaronic carriers move with the mobile chains. We have also observed the effect of source-drain voltage upon µ.Reference 1. F. Cicoira and C. Santato, Organic Electronics: Emerging Concepts and Technology, Wiley-VCH Verlag GmbH & Co. KGaA, 2013, Germany.2. A. Yelon, et al., Multi-excitation entropy: its role in thermodynamics and kinetics, Rep. Prog. Phys., 69, 1145-1194, 2006.3. E. J. Meijer, et al., The Meyer–Neldel rule in organic thin-film transistors, Appl. Phys. Lett., 76, 3433, 2000.4. J. C. Wang and Y. F. Chen, The Meyer–Neldel rule in fullerenes, Appl. Phys. Lett., 73, 948 1998.5. R. J. Chesterfield, et al., Organic Thin Film Transistors Based on N-Alkyl Perylene Diimides: Charge Transport Kinetics as a Function of Gate Voltage and Temperature, J. Phys. Chem. B, 108, 19281-19292, 2004.

Transport phenomena of Cu-S-Te chalcogenide nanocomposites: frequency response and AC conductivity.

In this work, the development and electrical characterization of several chalcogenide nanocomposites have been reported. X-ray diffraction (XRD) has been used to reveal their microstructures. Mott's variable range hopping model has been used to interpret the DC conductivity data of the nanocomposites at lower temperatures. The DC conductivity data at higher temperatures has been explained well using Greave's model. To explain the AC conductivity data, the Meyer-Neldel (MN) conduction rule has been employed. The AC conductivity spectra at different temperatures have been analyzed using Almond-West formalism. Different conduction models, namely, correlated barrier hopping (CBH) and modified non-overlapping small polaron tunneling (NSPT), have been used to interpret the conduction mechanism of the nanocomposites. Scaling of the AC conductivity spectra reveals that the electrical relaxation process is independent of temperature, but depends on the nanocomposite composition. The conductivity mechanism is explained using a schematic structural model.

Study of Metal-Induced Effects of Cd, Sb and Zn on d.c./a.c. Conduction and Photoconduction in Binary Se70Te30 Glass

This paper reports the temperature dependence of d.c. and a.c. conductivity in the glassy alloys of Se70Te30 and Se70Te28M2 (M = Cd, Sb, Zn). The role of the Cd, Sb, Zn elements as foreign atoms has been examined on the d.c./a.c. conduction and photoconduction in binary Se70Te30 glass. These multi-component chalcogenide glasses have been prepared by conventional, cost-effective and well-known melt-quench technique. Thermally activated a.c. conduction shows the presence of the compensation effect that is confirmed by the Meyer–Neldel relation between the associated activation energy and the pre-factor of a.c. conductivity. The metal-induced effects of Cd, Sb, Zn on the photosensitivity of parent glass are also discussed.

Thermal annealing and channel composition influences on the electrical properties of transparent-TFTs based on Zn-In-SnO ternary compound: Experiment and modeling

In this study, we present a quantitative analysis of the electrical properties of a series of bottom- gate top-contact n-channel transparent thin film transistors (TFTs) based on zinc indium tin oxide (Zn-In-SnO) ternary compound with various ZnO content. In addition, the effect of annealing on the TFTs electrical properties was examined theoretically and experimentally. The obtained results revealed that the thermal annealing of fabricated devices in air atmosphere at 300 °C has enhanced their performances; this behavior is well observed for all devices fabricated with different composition of Zn-In-SnO. TFTs having the lowest Zn content of 17.1% and annealed 300°C showed the high electrical performances in term of drain current, saturation mobility, threshold voltage. For the total resistance modeling of the fabricated devices with various content of ZnO and that annealed 300 °C, grain boundary model based on Meyer–Neldel rule was applied. The obtained results revealed that the total resistance was increased with increasing ZnO content. Furthermore, an analytical model has been refined in order to reproduce the current-voltage relationships of the fabricated TFTs using the overall resistance obtained from the NMR–GBT model. The calculated results are in good agreement with the experimental measurements of all fabricated devices. The obtained performance of TFTs based on zinc indium tin oxide with low content of ZnO and annealed will be promising for application in the future backplane of flat panel displays.

Electrically active boron doping in the core of Si nanocrystals by planar inductively coupled plasma CVD

An improvement in the doping efficiency in p-type nc-Si:H, a two-phase structure consisting of Si-nanocrystallites embedded in an amorphous matrix, has been pursued via low-temperature, spontaneous, plasma processing of low-pressure and high-density SiH4 plasma with added B2H6, diluted in H2, in inductively coupled plasma CVD. With increased dopant incorporation, the gradually reduced overall crystallinity systematically dominates via an ultrananocrystalline component in the thermodynamically stable ⟨220⟩ orientation. The microstructure factor decreases continuously, and the bonded-H content of the network increases arbitrarily, with a significant fraction being associated with Si in an Si-H-Si plateletlike configuration. Effective doping by B atoms, mostly in fourfold coordination with Si in its nanocrystalline core, contributes to the rapid increase in conductivity of the doped p-nc-Si:H network, up to a moderate B2H6 flow rate. However, gradually enhanced doping by threefold coordinated electrically inactive B-atoms, mostly at the nanocrystalline grain boundary at a higher B2H6 flow rate, induces gross structural deviation in the degree of nanocrystallinity and reduces dark conductivity substantially. Further, the logarithmic magnitude of the conductivity prefactor (σ0) demonstrates the negative characteristic energy (EMN) in the Meyer–Neldel (MN) relation. The high density of charge carriers in the heavily doped configuration of the nc-Si network forms a deep and continuous band tail near the valence-band edge and induces subsequent narrowing of the bandgap as well as a shift of the Fermi level into the valence band. Degenerate-semiconductor type behavior has been accomplished in a heavily doped p-nc-Si:H network, demonstrating reverse MN characteristics in electrical transport.

A Solid with Liquid-like Diffusion: A Unique Superionic Conductor

Understanding fast ionic diffusion in solids is key to engineering solid electrolytes for energy storage devices such as all-solid-state batteries. In this issue of Chem, Hautier and co-workers conduct atomistic modeling and nuclear magnetic resonance experiments to illustrate how the unique structure of LiTi2(PS4)3 enables unprecedented Li-ion diffusivity.

Accurate analytical model for effective carrier mobility of fully hydrogenated poly-si TFTs under White light illumination

The effect of illumination on the effective carrier’s mobility of fully hydrogenated polycrystalline silicon TFT is investigated theoretically as well as experimentally. The polysilicon layers are deposited by LPCVD technique in the amorphous state and then crystallized by a low temperature thermal annealing. Experimental data show that the illumination affects the channel mobility only in the subthreshold region. Based on this, an analytical effective mobility model under illumination is established. The results show that the mobility under illumination follows the Meyer–Neldel rule (MNR). The proposed model is verified with the experimental data. A good agreement is obtained.

Macroscopic Random Telegraph Noise

It is proposed that macroscopic telegraph noise in superconductors is due to dynamic coexistence of ordered and disordered vortex phases (DP and OP) created by edge contamination mechanism. A novel, robust, with bias insensitive rates, macroscopic telegraph noise in low Ca-doped manganites is ascribed to the dynamic current redistribution assisted by a positive resistance feedback associated with Meyer–Neldel compensation rule.

Single-Walled Carbon Nanotube-Controlled Meyer–Neldel Rules in Vanadium Oxide Films for Applications as Thermistor Materials in Sensors and Detectors

Owing to their excellent electrical properties, vanadium oxide (VOx) films are applied widely as thermistor materials in gas sensors and infrared detectors. The Meyer–Neldel rule (MNR) which was fi...

Studies on the photoelectric properties of crosslinked-poly(acrylamide co-acrylic acid) for photo detector applications

Abstract The co-polymer, polyacrylamide co-acrylic acid-P(AM-AA) was prepared by chemical polymerization of acrylamide with acrylic acid in presence of methylene bisacrylamide as a crosslinker. The copolymer was analyzed using FTIR, XRD and DTA. The I-V characteristics of the copolymer were studied and proved that the recombination process is dependent on the presence of traps distributed in the energy gap. The results showed that the traps contribute significantly in the increased photosensitivity of the co-polymer. The behaviors of both dark and photoconductivity with temperature showed linear relations at different light intensities and proved an activated conduction with single activation energy. The activation energy (Ea) at different light intensity was found to follow Meyer Neldel rule (MN rule) and the intercept σo (pre factor) as well. The characteristic energy of exponential traps was found to be within 0.0134–0.009 eV, at different light intensities. The transient photoconductivity studies on the co-polymer confirmed the presence of traps. Where, the high photosensitivity and the presence of traps may contribute to the development of the improved performance of photo detectors.

Organic insulator layer influence on the electrical properties of N, N’-di (2-ethylhexyl) - 3, 4, 9, 10-perylene diimide organic thin-film transistors: Experiment and modeling

In this work, n- type organic thin film transistors (OTFTs) based on different kinds of organic dielectrics were fabricated, characterized and theoretically investigated. Three kinds of organic insulators were applied as dielectric gate which are: divinyl tetramethyl disiloxane-bis (benzo-cyclobutene) (BCB), poly(vinylalcohol) (PVA) and poly (4-vinyl phenol) (PVP). Analytical model was applied to describe the electrical behavior of the fabricated OTFTs and to explain the absence of saturation of the drain current for the device based on PVA dielectric. In addition, Meyer–Neldel rule-grain boundary model was applied for the calculation of total resistance of OTFTs based on different dielectrics materials. The theoretical results of output characteristics and total resistance showed an excellent agreement with the experimental measurements. The experimental and theoretical calculations revealed that the n-channel OTFTs based on BCB as an insulator layer exhibited superior electrical characteristics in terms of threshold voltage, mobility and drain current compared with the devices based on PVA and PVP as a gate insulator layer. The device based on BCB organic insulator layer has the largest mobility of 4 × 10−3 cm2 V−1 s−1, the smallest leakage current relative to the devices based on PVA and PVP. While, the device fabricated with PVP organic insulator gate has a large trap density on the PVP-EHPDI interface which causes a pronounced decrease in field effect mobility and consequently drain current.