Papers by Keyword: Electron Transport

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Authors: Michael Winters, E.B. Thorsteinsson, Einar Ö. Sveinbjörnsson, H.P. Gislason, Jawad Hassan, Erik Janzén, Niklas Rorsman
Abstract: The carrier velocity is measured as a function of electric field in as-grown and H-intercalaed epitaxial graphene grown on semi-insulating 4H-SiC in order to estimate the low field carrier mobility as a function of temperature. The mobility is also measured on the same samples as a function of temperature in a liquid Helium (He) cooled cryostat. The two temperature dependent measurements are compared in order to deduce the dominant carrier scattering mechanisms in both materials. In as-grown material, acoustic phonon scattering and impurity scattering both contribute, while impurity scattering dominates in H-intercalated material.
Authors: Ajay K. Jena, Shyama Prasad Mohanty, Parag Bhargava
Abstract: TiO2 films, which are often sintered at 450°C for 30 or 60 minutes for application in dye-sensitized solar cells (DSSCs), show no appreciable connectivity between the TiO2 particles. The present work deals with connectivity between TiO2 particles and its effect on electron diffusion and short circuit current density (Jsc) of DSSCs made from TiO2 films sintered at lower temperature for longer time (450°C, 550°C, 650°C for 60 minutes) and higher temperature for shorter time (450°C for 60 min followed by 700°C and 800°C for 10 and 20 minutes). TiO2 films sintered at higher temperature (700°C) but for shorter time (10 min) exhibited better connectivity between the particles with slight reduction in surface area. This caused faster transport of electron through the films sintered at 700°C/10 min than 450°C/60 min and 550°C/60 min and hence, resulted in highest Jsc (~ 7 mA/cm2). Films sintered at 650°C/60 min and 700°C/20 min showed better interparticle connectivity but had significantly lower surface area, dye loading and therefore, despite faster diffusion of electron in these films Jsc was measured to be lower. Sintering at 700°C/10 min following 450°C/60 min could be considered the best in terms of dye loading, electron transport and efficiency.
Authors: A.A. Evtukh, O. Bratus
Abstract: The electrical properties of nanocomposite SiO2(Si) films containing Si nanoclusters have been investigated. The films were formed by oxide assisted growth that included ion plasma sputtering (IPS) of Si target and following high temperature annealing. It was determined that electrical conductivity of the films correspond to the mechanism of hopping conductivity with variable hopping length through the traps near the Fermi level (Mott mechanism) due to the large number of silicon dangling bonds in the dielectric matrix. The peculiarities of charge capture in nanocomposite SiO2(Si) films for their application as the medium for charge storage in memory cells have been investigated by C-V method. The good charge storage possibility of SiO2(Si) films formed by IPS deposition with followed temperature annealing has been observed. The negative differential capacitance has been revealed in conditions of semiconductor surface accumulation. The physical model for explanation of the negative differential capacitance of MIS structures with nanocomposite SiO2(Si) films as the dielectric has been proposed. The model is based on the parallel conjunction of the oxide capacitance and nanocrystals capacitance.
Authors: A.V. Afanasyev, V.A. Ilyin, V.V. Luchinin, A.S. Petrov
Abstract: 3C-SiC (n) / Si (p) heterostructures were obtained and investigated in a wide temperature range. It was shown, the main mechanisms of charge transport diffusion and recombination. The properties of silicon substrate were determining the working temperature range of investigated diodes. Therefore the rectifying properties of 3С-SiC(n)/Si(p) diodes were stable only up to 473 K. Two sites with different activation energies were observed on the Jrev(1/T) curves at fixed voltage: 0,32 eV which, characterized states on the SiC/Si interface, Е2 ≈ 0,55 eV which corresponds to the middle of silicon bandgap and defines existence of reverse current generation component.
Authors: K. Pękała, P. Jaśkiewicz, M. Pękała, Tadeusz Kulik
Authors: Yan Wei Li, Jin Huan Yao, Xing Sheng Deng, Xiao Xi Huang
Abstract: The nonequilibrium Green’s function approach in combination with density-functional theory is used to perform ab inito quantum-mechanical calculations of the electron transport properties of porphyrin oligomers sandwiched between two gold electrodes. The results show that porphyrin oligomers are good candidates for long-range conduction wires. In particular, the decay of conductance of porphyrin oligomers does not follow the exponential relation. The electron transport behavior was analyzed from the molecular projected self-consistent Hamiltonian states and the electron transmission spectra of the molecular junctions.
Authors: Yan Wei Li, Jin Huan Yao, Sheng Kui Zhong, Ji Qiong Jiang, Xiao Xi Huang
Abstract: The electron transport behavior of a short graphene nanoribbon sandwiched between two gold(111) electrodes is investigated using density functional theory calculations and nonequilibrium Green’s function technique. The calculated current-voltage characteristic of the graphene nanoribbon junction shows an obvious negative differential resistance (NDR) phenomenon. The mechanism of this NDR behavior of graphene nanoribbon is discussed in terms of the evolution of the molecular energy levels, the spatial distribution of frontier molecular orbitals, and the electron transmission spectra under various applied biases. It is found that the changes of the spatial distribution of molecular orbitals near Fermi level with the applied bias lead to such NDR behavior.
Authors: Viktor Gružinskis, Jian Hui Zhao, P. Shiktorov, E. Starikov
Authors: F. Edelman, T. Raz, Y. Komem, M. Stölzer, P. Zaumseil
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