Electron Transport Characteristics Research Articles

Electrical characteristics of amyloid beta peptides in vertical junctions

Assembled amyloid beta (Aβ) peptides have been considered pathological assemblies involved in human brain diseases, and the electron transfer or electron transport characteristics of Aβ are important for the formation of structured assemblies. Here, we report the electrical characteristics of surface-assembled Aβ peptides similar to those observed in Alzheimer’s patients. These characteristics correlate to their electron transfer characteristics. Electrical current–voltage plots of Aβ vertical junction devices show the Aβ sequence dependence of the current densities at both Aβ monomers (mono-Aβs) and Aβ oligomers (oli-Aβs), while Aβ sequence dependence is not clearly observed in the electrical characteristics of Aβ planar field effect transistors (FETs). In particular, surface oligomerization of Aβ peptides drastically decreases the activity of electron transfer, which presents a change in the electron transport pathway in the Aβ vertical junctions. Electron transport at oli-Aβ junctions is symmetric (tunneling/tunneling) due to the weak and voltage-independent coupling of the less redox-reactive oli-Aβ to the contacts, while that at mono-Aβ junctions is asymmetric (hopping/tunneling) due to redox levels of mono-Aβ voltage-dependently coupled with contact electrodes. Consequently, through vertical junctions, the sequence- and conformation-dependent electrical characteristics of Aβs can reveal their electron transfer activities.

Summary of New Insight into Electron Transport in Metals

This paper gives a summary of a new insight into basic electron transport characteristics in crystalline elemental metals. The general expressions based on the Fermi-Dirac distribution of the effective density of the randomly moving electrons, their diffusion coefficient, drift mobility, and other characteristics, including the Einstein relation between diffusion coefficient and drift mobility, are presented. It is shown that the creation of the randomly moving electrons due to lattice atom vibrations produces the same number of electronic defects, which cause scattering of the randomly moving electrons and related transport characteristics.

Bound state energy of finger gate and top gate with consideration of Rashba-Dresselhaus-Zeeman effects

The spintronic effect of quantum transport is investigated in a fully-depleted spin transistor. The analysis considers the Zeeman effect caused by an external planar magnetic field and the electron transport characteristics induced under Rashba-Dresselhaus spin-orbit coupling. A transcendental equation is proposed for predicting the bound state energies of the conductance structure produced under the strong Rashha-Desselhaus-Zeeman effect. It is shown that the proposed equation provides an accurate means of predicting the bound state energy as a function of the potential energy and top gate length.

Mechanism of Defect Formation in Zr1 – xVxNiSn Thermoelectric Material

Crystal and electronic structure, transport and energy state characteristics of the Zr1−xVx NiSn (0.01 ≤ x ≤ 0.1) thermoelectric material are investigated in the 80–400 K temperature interval. A mechanism of simultaneous generation of structural defects of the acceptor and donor nature, which determines the electric conductivity of the material, is established. It is shown that energetically expedient is a simultaneous occupation of the 4c position of Ni (3d84s2) atoms by V (3d34s2) atoms, which generates structural defects of the acceptor nature and the impurity acceptor band Ꜫ1A, as well as the 4a position of Zr (4d25s2) atoms, generating structural defects of the donor nature and the impurity donor band Ꜫ2D.

Detection of DNA Bases via Field Effect Transistor of Graphene Nanoribbon With a Nanopore: Semi-Empirical Modeling.

DNA sequencing techniques are critical in order to investigate genes' functions. Obtaining fast, accurate, and affordable DNA bases detection makes it possible to acquire personalized medicine. In this article, a semi-empirical technique is used to calculate the electron transport characteristics of the developed z-shaped graphene device to detect the DNA bases. The z-shaped transistor consists of a pair of zigzag graphene nanoribbon (ZGNR) connected through an armchair graphene nanoribbon (AGNR) channel with a nanopore where the DNA nucleobases are positioned. Non-equilibrium Green's function (NEGF) integrated with semi-empirical methodologies are employed to analyze the different electronic transport characteristics. The semi-empirical approach applied is an extension of the extended Hückel (EH) method integrated with self-consistent (SC) Hartree potential. By employing the NEGF+SC-EH, it is proved that each one of the four DNA nucleobases positioned within the nanopore, with the hydrogen passivated edge carbon atoms, results in a unique electrical signature. Both electrical current signal and transmission spectrum measurements of DNA nucleobases inside the device's pore are studied for the different bases with modification of their orientation and lateral translation. Moreover, the electronic noise effect of various factors is studied. The sensor sensitivity is improved by using nitrogen instead of hydrogen to passivate the nanopore and by adding a dual gate to surround the central semiconducting channel of the z-shaped graphene nanoribbon.

LIGHT ENERGY UTILIZATION AND CHLOROPHYLL FLUORESCENCE IN TWO CROSSBREED POPLARS

Aims Our objective was to study two widely planted hybrid poplars,Populus deltaids 'cv-64' (P64) and P. simonii canaden × P. russkii-9 (Jia),to explore their growth mechanisms and the solar energy utilization by photosystem II (PSII) antennae to thermal energy dissipation and photosyn-thetic electron transport characteristics during long-term adaptation to the ambient environment. Methods We studied energy utilization by computing chlorophyll fluorescence parameters and photo-synthesis. Plants were grown at the Plain Forest Farm Nursery of the State Forestry Bureau of Ili Autonomous Prefecture in China's Xinjiang region. Important findings The diurnal changes of net photosynthesis (Pn) were bimodal and had a 20.1% gap under high photon flux density (PFD). The actual efficiency of open PSII centers (ΦPSII) were all of the "U" type,and their average values were equal. The ΦPSII of P64 and Jia reached the minimum value at 16:30 and 14:30,respectively. The closure value had one wave hollow at 14:30,and there was no significant difference (p0.05) in whole-day average values. The non-photochemical quenching co-efficients (NPQ) all achieved the maximum value at 16:30. Jia's NPQ maximum was less than that of P64,and the whole-day NPQ difference reached 31.7%. The estimated rates of photochemistry (E.P) and non-photochemistry (E.D) showed that under the lower PFD the poplars used more than 50% of theabsorbed solar energy for the photochemical quenching,and under high PFD the absorbed solar energy for P64 for the photochemical quenching is greater than the proportion for Jia,while the absorbed solar energy for P64 for heat dissipation is less than the proportion for Jia. The E.P had no difference and reached the maximum estimated value when its E.D reached the maximum. P64 tended to use more ab-sorbed solar energy for photochemical quenching,but Jia tended to use more solar energy for non-photochemical quenching. The cumulative values and average values of the Pn for Jia were much larger than values for P64,but the absorbed solar energy of P64 is greater than the proportion of Jia for the photochemical quenching. These results prove that it is inadequate to calculate the absorbed energy only by the chloroplast fluorescent characteristics of light received.

Link between Gas Phase Reaction Chemistry and the Electronic Conductivity of Atomic Layer Deposited Titanium Oxide Thin Films.

In situ monitoring of gas phase composition reveals the link between the changing gas phase chemistry during atomic layer deposition (ALD) half-cycle reactions and the electronic conductivity of ALD-TiO2 thin films. Dimethylamine ((CH3)2NH, DMA) is probed as the main product of both the TDMAT and water vapor half-reactions during the TDMAT/H2O ALD process. In-plane electronic transport characterization of the ALD grown films demonstrates that the presence of DMA, a reducing agent, in the ALD chamber throughout each half-cycle is correlated with both an increase in the films' electronic conductivity, and observation of titanium in the 3+ oxidation state by ex situ X-ray photoelectron spectroscopy analysis of the films. DMA annealing of as-grown TiO2 films in the ALD chamber produces a similar effect on their electronic characteristics, indicating the importance of DMA-induced oxygen deficiency of ALD-TiO2 in dictating the electronic conductivity of as-grown films.

Weighted Mobility Ratio Engineering for High-Performance Bi-Te-Based Thermoelectric Materials via Suppression of Minority Carrier Transport.

Thermoelectrics, which can generate electricity from a temperature difference, or vice versa, is a key technology for solid-state cooling and energy harvesting; however, its applications are constrained owing to low efficiency. Since the conversion efficiency of thermoelectric devices is directly obtained via a figure of merit of materials, zT, which is related to the electronic and thermal transport characteristics, the aim here is to elucidate physical parameters that should be considered to understand transport phenomena in semiconducting materials. It is found that the weighted mobility ratio of the majority and minority carrier bands is an important parameter that determines zT. For nanograined Bi-Sb-Te alloy, the unremarked role of this parameter on temperature-dependent electronic transport properties is demonstrated. This analysis shows that the control of the weighted mobility ratio is a promising way to enhance zT of narrow bandgap thermoelectric materials.

Efficient oxygen evolution catalysts with synergistic reactivity: CoFe2O4/C derived from bimetallic organic framework supported on nitrogen-doped carbon nanoarray structure

Here, we covered a polyaniline nanowire array (denoted as PANI) on carbon paper (denoted as CP) by a electrochemical polymerization method, directly grown MOF-74-Co/Fe on its surface and pyrolyzed to form the CoFe2O4/C supported on nitrogen-doped carbon nanoarray materials (denoted as NC-CoFe2O4/C@CP), which is prepared a highly active and stable OER catalyst. PANI can not only be used as a “binder”, grow MOF on its surface and cover the carbon paper, but also improve the conductivity and stability of the material by forming nitrogen-doped carbon after pyrolysis. And its unique 3D nano-array structure not only greatly increases the surface area, but also provides more attachment sites for CoFe2O4, thereby accelerating electron transport and improving OER performance. High specific surface area, high utilization of the catalyst, enhanced electron transport characteristics and retention characteristics of the original carbon paper characteristics ensure excellent OER activity. The final sample exhibits outstanding activity for OER in alkaline solution, accompanied by a low onset potential about 1.52 V (vs reversible hydrogen electrode), and the small Tafel slope of 70 mV dec−1. In particular, after 21600s, the current drop is negligible, which is means that the NC-CoFe2O4/C@CP catalyst has the high stability. Density Functional Theory (DFT) calculation reveals the main surface adsorbent of CoFe2O4 is OH*, and the surface Co atoms are the main active sites.

Effects of inelastic interaction of the non-equilibrium electrons with the neutral impurities on the non-ohmic characteristics of a compensated semiconductor compound at low lattice temperatures

Low lattice temperature has some distinct features which are hardly observed at high temperatures. These features significantly change the electron transport characteristics of a semiconductor. The inelasticity of the collision of non-equilibrium electrons with the neutral impurities is one of such features. The effects of this inelasticity on the average rate of loss of energy of such an electron have been studied here for a non-degenerate and compensated semiconductor compound, adopting the well-known standard method. The results for the electric field dependence of the effective temperature of the electrons have also been obtained here from the solution of the energy balance equation of the electron-lattice system. The numerical data for InSb, InAs and GaSb, which follow from the present analysis, reveal that the effects are significant. The results are seen to be in satisfactory agreement with the experimental observations.

Spin filtering and magnetically-controlled quantum switch in multiple triangular rings consisting of quantum dots

Electron transport characteristics through a system consisting of a series of triangular quantum dot rings are studied utilizing the non-equilibrium Green’s function. In the presence of a magnetic field, an additional anti-resonance point occurs in the conductance spectrum. As the number of triangular quantum dot rings increases, two anti-resonance points evolve into two well-defined insulating bands. The insulating band disappears as the magnetic flux takes an appropriate value, and therefore, an effective magnetically-controlled quantum switch can be achieved. If a Zeeman magnetic field is introduced, a spin-polarized window (SPW) can be formed, suggesting a physical scheme of a spin filtering. As the intradot Coulomb interactions are taken into consideration, more SPWs can be obtained. This work sheds lights onto the design of future quantum devices.

Electronic structure and transport properties of coupled CdS/ZnSe quantum dots

Electronic structure and transport characteristics of coupled CdS and ZnSe quantum dots are studied using density functional theory and non equilibrium Greens function method respectively. Our investigations show that in these novel coupled dots, the Frontier occupied and unoccupied molecular orbitals are spatially located in two different parts, thereby indicating the possibility of asymmetry in electronic transport. We have calculated electronic transport through the coupled quantum dot by varying the coupling strength between the individual quantum dots in the limits of weak and strong coupling. Calculations reveal asymmetric current vs voltage curves in both the limits indicating the rectifying properties of the coupled quantum dots. Additionally we discuss the possibility to tune the switching behavior of the coupled dots by different gate geometries.

Charge transfer enhancement between the Pt electrode and the ferroelectric BaTiO3 phase sensors

BaTiO3 is a ferroelectric sensor in the piezoelectric transforming conditions. In this study, we focused on the electron transport characteristics in the interface between the Pt and the BaTiO3, which enhanced the conductive properties of BaTiO3. This approach will be more helpful to transfer the piezoelectric signal and may offer some new suggestion of the conductive behavior of the BaTiO3 molecular.

Low-temperature hall effect and martensitic transition temperatures in magnetocaloric Ni50Mn35Sb15−xGex (x = 0, 1, 3) alloys

The field dependence of Hall resistivity ρH and magnetization M of the magnetocaloric Ni50Mn35Sb15−xGex (x = 0, 1, 3) alloys were measured at T = 4.2 K and in magnetic fields of up to 70 kOe. The martensitic transitions temperatures, i.e., the martensite start temperature MS, martensite finish temperature MF, austenite start AS and austenite finish AF temperatures, were obtained from the magnetization temperature dependence that measured from 4.2 to 350 K in a field of 1 kOe. It was observed that the martensitic transitions temperatures correlate strongly both with the valence electron concentration e/a and with the electronic transport characteristics, which are the coefficients of normal R0 and anomalous RS Hall effect and the concentration of charge carriers n. Apparently, similar correlations should be observed in other magnetocaloric compounds that could be used to study martensitic transitions.

Electronic and thermal transport in novel carbon-based bilayer with tetragonal rings: a combined study using first-principles and machine learning approach.

In this article, the structural, electronic and thermal transport characteristics of bilayer tetragonal graphene (TG) are systematically explored with a combination of first-principles calculations and machine-learning interatomic potential approaches. Optimized ground state geometry of the bilayer TG structure is predicted and examined by employing various stability criteria. Electronic bandstructure analysis confirmed that bilayer TG exhibits a metallic band structure similar to the monolayer T-graphene structure. Thermal transport characteristics of the bilayer TG structure are explored by analysing thermal conductivity, the Seebeck coefficient, and electrical conductivity. The electronic part of the thermal conductivity shows linearly increasing behaviour with temperature, however the lattice part exhibits the opposite character. The lattice thermal conductivity part is investigated in terms of the three phonon scattering rates and weighted phase space. On the other hand, the Seebeck coefficient goes through a transition from negative to positive values with increasing temperature. The Wiedemann-Franz law regarding electrical transport of the bilayer TG is verified and confirms the universal Lorentz number. Specific heat of the bilayer TG structure follows the Debye model at low temperature and constant behaviour at high temperature. Moreover, the Debye temperature of the bilayer TG structure is verified by ab initio calculations as well as fitting the specific heat data using the Debye model.

Exploration of electron transport behaviour of a push-push anil for possible application as an optical material

Abstract The present work delineates the relationship between the structural and spectral parameters of an anil, salicylidene-orthochloroaniline through the determination of its optimized structure, and consequential theoretical parameters using Density Functional Theory (B3LYP/6-311G (d, p) level) and spectral characteristics through UV–visible studies. The time-dependent DFT was used to calculate the theoretical UV–visible spectra and compared with the experimental spectra. The different frontier molecular orbitals and their energy gaps were elucidated and correlated with the experimentally determined values. Cyclic voltammetry confirmed the electron transport characteristics of the molecule. The anil followed a single electron transport process, which is irreversible, and diffusion-controlled. The overall study indicated that the anil could be suitably exploited as an optical material for electronic devices.

A Temperature Stable Amplifier Characteristics of AlGaN/GaN HEMTs on 3C-SiC/Si

A high temperature stable amplifier characteristics for L-band or 2 GHz was studied using AlGaN/GaN high electron mobility transistors (HEMTs) on 3C-SiC/Si substrate. A crack free, high quality AlGaN/GaN heterostructure on a 6-inch Czochralski (Cz)-Si substrate was realized by metal oxide chemical vapor deposition (MOCVD). The epitaxial structure comprises an $8~\mu \text{m}$ thick nitride layer and a $1~\mu \text{m}$ thick 3C-SiC intermediate layer. The fabricated AlGaN/GaN HEMT achieved excellent electron transport characteristics along with a comparable cutoff frequency ( ${f}~_{\text {T}}$ ) of 4.8 GHz for $2~\mu \text{m}$ gate length device. Temperature dependent S-parameter measurement of open pad structures achieved outstanding temperature stability up to $125~^\circ \text{C}$ . Continuous wave power measurements showed a 2 GHz continuous wave power density of 2 W/mm, a maximum power added efficiency (PAE) of 47% along with a linear gain of 17.2 dB for class A amplifier operation. Moreover, at elevated temperature of up to $125~^\circ \text{C}$ , the minimal power performance degradation was mainly attributed to the intrinsic property of the device, thus elimination of RF leakage from the buffer or epitaxial layers at high temperatures was confirmed.

Influences of the number of 2-ethylhexylamine chain substituents on electron transport characteristics of core-substituted naphthalene diimide analogues

We designed and synthesized a series of naphthalenediimide (NDI) derivatives through core-substitution (coded as cNDI) with various number of 2-ethyl-hexylamine (EHA) chains at different positions and examined electron mobility properties.

Hot Electron Transport Characteristics in a Conical-Entry-Multilayer Target Driven by Intense Laser

Hot Electron Transport Characteristics in a Conical-Entry-Multilayer Target Driven by Intense Laser

Four probe electron transport characteristics of porphyrin phenylacetylene molecular devices

A novel functional nano-electronic molecular system by tuning gate voltages and source voltages as well as changing lead-to-lead channels.