Modeling of electronic transport in nanostructures
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Doctoral thesis (article-based)
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en
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48, [42]
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Dissertations / Laboratory of Physics, Helsinki University of Technology, 135
Abstract
Nanometer-scale electronic devices are building blocks of future electronics. The function of these components is based on quantum-mechanical phenomena and therefore new modeling methods has to be developed to model properties of nano-devices. In this thesis one solution and implementation is presented. In this thesis transport properties of the nano-devices are modeled using the density-functional theory. In the main part of the work electron densities and currents calculated using the Green's function method. The method enables the connection of the nanostructure to the semi-infinite leads by the open boundary conditions making finite-size effects small. Electron currents under finite bias conditions can also be calculated. The use of the Green's function method is computationally heavy in comparison to the explicit wave-function methods. An important part of this thesis work is to choose efficient numerical methods and their implementation. The computer code created has one-, two- and three-dimensional versions so that different types of nanostructures can be modeled. The oneand two-dimensional versions use the effective mass approximation while the three-dimensional one uses nonlocal pseudopotential operators. The numerical implementation is done using the finite-element method with the so-called hp-elements. The codes implemented are used to model magnetic resonance tunneling diodes, two-dimensional quantum wires, Na-atom chains and thin HfO2 layers.Description
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Parts
- P. Havu, T. Torsti, M. J. Puska, and R. M. Nieminen, Conductance oscillations in metallic nanocontacts, Physical Review B 66, 075401 (2002) (5 pages). [article1.pdf] © 2002 American Physical Society. By permission.
- P. Havu, V. Havu, M. J. Puska, and R. M. Nieminen, Nonequilibrium electron transport in two-dimensional nanostructures modeled using Green's functions and the finite-element method, Physical Review B 69, 115325 (2004) (13 pages). [article2.pdf] © 2004 American Physical Society. By permission.
- P. Havu, M. J. Puska, R. M. Nieminen, and V. Havu, Electron transport through quantum wires and point contacts, Physical Review B 70, 233308 (2004) (4 pages). [article3.pdf] © 2004 American Physical Society. By permission.
- P. Havu, N. Tuomisto, R. Väänänen, M. J. Puska, and R. M. Nieminen, Spin-dependent electron transport through a magnetic resonant tunneling diode, Physical Review B 71, 235301 (2005) (12 pages). [article4.pdf] © 2005 American Physical Society. By permission.
- P. Havu, V. Havu, M. J. Puska, M. H. Hakala, A. Foster, and R. M. Nieminen, Finite-element implementation for electron transport in nanostructures, Journal of Chemical Physics, submitted for publication (9 pages). [article5.pdf] © 2005 by authors and © 2005 American Institute of Physics. By permission.