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Tunneling transport in devices with semiconducting leads  [PDF]
Emil Prodan,Amy LeVee
Physics , 2009, DOI: 10.1103/PhysRevB.81.085307
Abstract: This paper extends the modern theory of tunneling transport to finite temperatures. The extension enables applications to molecular electronic devices connected to semiconducting leads. The paper presents an application of the theory to molecular devices made of alkyl chains connected to silicon nano-wires, mapping their transport characteristics as functions of temperature and alkyl chain's length. Based on these calculations and on the analytic theory, it is found that the tunneling decay constant is determined not by the Fermi level, but by the edge of the valence or conductance band, whichever is closer to the Fermi level. Further insight is provided by mapping the evanescent transport channels of the alkyl chains and few other physical quantities appearing in the analytic formula for conductance. A good qualitative agreement with the experimental data is obtained.
Thermoelectric properties of disordered graphene antidot devices  [PDF]
Tue Gunst,Jing-Tao Lü,Troels Markussen,Antti-Pekka Jauho,Mads Brandbyge
Physics , 2012, DOI: 10.1109/IWCE.2012.6242835
Abstract: We calculate the electronic and thermal transport properties of devices based on finite graphene antidot lattices (GALs) connected to perfect graphene leads. We use an atomistic approach based on the $\pi$-tight-binding model, the Brenner potential, and employing recursive Green's functions. We consider the effect of random disorder on the electronic and thermal transport properties, and examine the potential gain of thermoelectric merit by tailoring of the disorder. We propose several routes to optimize the transport properties of the GAL systems. Finally, we illustrate how quantum thermal transport can be addressed by molecular dynamics simulations, and compare to the Green's function results for the GAL systems in the ballistic limit.
Tailoring multilayer quantum wells for spin devices  [PDF]
S. Ullah,G. M. Gusev,A. K. Bakarov,F. G. G. Hernandez
Physics , 2015,
Abstract: We investigate long-lived spin coherence of a high mobility dense two-dimensional electron gas in multilayer GaAs quantum wells. The dynamics of the spin polarization was optically studied using pump-probe techniques: time-resolved Kerr rotation and resonant spin amplification. For samples doped beyond the metal-to-insulator transition, long dephasing time in the few nanoseconds range was obtained in double and triple quantum wells by tailoring the spin-orbit interaction. The determination of the scales: transport scattering time, single-electron scattering time, electron-electron scattering time, and the spin polarization decay time with and without magnetic field further supports the possibility of using n-doped multilayer systems for developing spin devices.
Environmental Effects on Electronic Devices in Mexico  [PDF]
Francisco Sánchez Pérez, Armando Ortiz Prado
Materials Sciences and Applications (MSA) , 2019, DOI: 10.4236/msa.2019.103020
Abstract: This paper shows the results of the assessment of impairment suffered by elements of electronic equipment by environmental effects in different climatic zones of Mexico. For this study, evaluated devices were evaluated that are mostly exposed under different climatic conditions of operation, to determine the degree of damage suffered which leads to malfunction, reduced service life and loss of information in some cases. The main contribution is to identify the causes of the deterioration to delay the effect of atmospheric corrosion deterioration in electronic components. The Mexican Republic has a wide range of climates and subclimates over its territory, sampling was performed for each one of the most representative regions, by their nature tend to be more conducive to the release of corrosive effect on the computer and electronic devices. For the determination of existing impairment in electronic equipment, a methodology is proposed for the evaluation of samples taken from each region, determining the degree of corrosion that exists in these devices. It should be noted that according to the literature, the main pollutants that lead to the deterioration caused by corrosive environmental phenomena are SO2, NOx, CO, CO2, coupled with the presence of ozone and chloride, characteristic of the coastal region, combined with the percent relative humidity (% HR), and temperature cycles as reported by environmental monitoring systems in Mexico. With the study of atmospheric corrosivity in electronic devices has been determined: 1) Design and operation of chamber to accelerated atmospheric corrosion testing. 2) Identification of electronic components with increased susceptibility to corrosive phenomena under typical environmental different regions of Mexico. 3) Correlation of damage suffered in electronic equipment under typical operating conditions and accelerated tests. 4) Determining the degree of atmospheric corrosion on electronic equipment. 5) Construction of atmospheric corrosivity map for Mexico in electronic devices.
First-principles calculation of electronic structure of MgxZn1-xO codoped with aluminium and nitrogen

Zhang Ming,Zhang Chuan-Hui,Shen Jiang,

中国物理 B , 2011,
Abstract: Aiming at developing p-type semiconductors and modulating the band gap for photoelectronic devices and band engineering, we present the ab initio numerical simulation of the effect of codoping ZnO with Al, N and Mg on the crystal lattice and electronic structure. The simulations are based on the Perdew--Burke--Ernzerhof generalised-gradient approximation in density functional theory. Results indicate that electrons close to the Fermi level transfer effectively when Al, Mg, and N replace Zn and O atoms, and the theoretical results were consistent with the experiments. The addition of Mg leads to the variation of crystal lattice, expanse of energy band, and change of band gap. These unusual properties are explained in terms of the computed electronic structure, and the results show promise for the development of next-generation photoconducting devices in optoelectronic information science and technology.
Tunable Hybridization Between Electronic States of Graphene and Physisorbed Hexacene  [PDF]
Yuefeng Yin,Jiri Cervenka,Nikhil V. Medhekar
Physics , 2015,
Abstract: Non-covalent functionalization via physisorption of organic molecules provides a scalable approach for modifying the electronic structure of graphene while preserving its excellent carrier mobilities. Here we investigated the physisorption of long-chain acenes, namely, hexacene and its fluorinated derivative perfluorohexacene, on bilayer graphene for tunable graphene devices using first principles methods. We find that the adsorption of these molecules leads to the formation of localized states in the electronic structure of graphene close to its Fermi level, which could be readily tuned by an external electric field. The electric field not only creates a variable band gap as large as 250 meV in bilayer graphene, but also strongly influences the charge redistribution within the molecule-graphene system. This charge redistribution is found to be weak enough not to induce strong surface doping, but strong enough to help preserve the electronic states near the Dirac point of graphene.
Tailoring electronic structure of polyazomethines thin films  [PDF]
J. Weszka,B. Hajduk,M. Domański,M. Chwastek
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The aim of this work is to show how electronic properties of polyazomethine thin films deposited by chemical vapor deposition method (CVD) can be tailored by manipulating technological parameters of pristine films preparation as well as modifying them while the as-prepared films put into iodine atmosphere.Design/methodology/approach: The recent achievements in the field of designing and preparation methods to be used while preparing polymer photovoltaic solar cells or optoelectronic devices.Findings: The method used allow for pure pristine polymer thin films to be prtepared without any unintentional doping taking place during prepoaration methods. This is a method based on polycondensation process, where polymer chain developing is running directly due to chemical reaction between molecules of bifunctional monomers. The method applied to prepare thin films of polyazomethines takes advantage of monomer transporting by mreans of neutral transport agent as pure argon is.Research limitations/implications: The main disadvantage of alternately conjugated polymers seems to be quite low mobility of charge carrier that is expected to be a consequence of their backbone being built up of sp2 hybridized carbon and nitrogen atoms. Varying technological conditions towards increasing reagents mass transport to the substrate is expected to give such polyazomethine thin films organization that phenylene rin stacking can result in special π electron systems rather than linear ones as it is the case.Originality/value: Our results supply with original possibilities which can be useful in ooking for good polymer materials for optoelectronic and photovoltaic applications. These results have been gained on polyazomethine thin films but their being isoelectronic counterpart to widely used poly p-phenylene vinylene may be very convenient to develop high efficiency polymer solar cells
Electronic structure of a graphene superlattice with a modulated Fermi velocity  [PDF]
Jonas R. F. Lima
Physics , 2015, DOI: 10.1016/j.physleta.2015.02.034
Abstract: The electronic structure of a graphene superlattice composed by two periodic regions with different Fermi velocity, energy gap and electrostatic potential is investigated by using an effective Dirac-like Hamiltonian. It must be expected that the change of the Fermi velocity in one region of the graphene superlattice is equivalent to changing the width of this region keeping the Fermi velocity unchanged, provided that the time taken to charge carriers cross the region is the same. However, it is shown here that these two systems are not equivalent. We found extra Dirac points induced by the periodic potential and their location in the \textbf{k} space. It is shown that the Fermi velocity modulation breaks the symmetry between the electron and hole minibands and that it is possible to control the behavior of the extra Dirac points. The results obtained here can be used in the fabrication of graphene-based electronic devices.
Tuning electronic structure of graphene via tailoring structure: theoretical study  [PDF]
H. Y. He,Y. Zhang,B. C. Pan
Physics , 2010, DOI: 10.1063/1.3437092
Abstract: Electronic structures of graphene sheet with different defective patterns are investigated, based on the first principles calculations. We find that defective patterns can tune the electronic structures of the graphene significantly. Triangle patterns give rise to strongly localized states near the Fermi level, and hexagonal patterns open up band gaps in the systems. In addition, rectangular patterns, which feature networks of graphene nanoribbons with either zigzag or armchair edges, exhibit semiconducting behaviors, where the band gap has an evident dependence on the width of the nanoribbons. For the networks of the graphene nanoribbons, some special channels for electronic transport are predicted.
Application of nanoscratching in electronic devices  [PDF]
Maria Ramiaczek-Krasowska,Adam Szyszka,Joanna Prazmowska,Regina Paszkiewicz
Optica Applicata , 2009,
Abstract: The lithography is a basic operation in the fabrication process of semiconductor devices. The scaling ability is the reason why the atomic force microscopy (AFM) nanolithograpy is currently studied in many laboratories. In the paper, the results of the mechanical AFM lithography, named nanoscribing or nanoscratching, are presented. In this method, the pattern is created by mechanical interaction between the AFM tip and a sample. This interaction requires the application of large forces in micronewtons scale.
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