Modelling of Quantum Transport in Nanostructures
(2002) Abstract
 In this thesis, theoretical studies of the transport properties of three nanoscale systems: onedimensional (1D) quantum wires (QWRs), zerodimensional (0D), laterally confined, doublebarrier resonant tunnelling structures (DBRTSs) and threeterminal ballistic junctions (TBJs), have been performed. In the first part of the thesis, an overview of the realization and properties of such systems is given along with a description of modelling tools used in the calculations. The second and main part of the thesis contains the original research results, summarized into seven papers.
The conductance of QWRs with corrugated boundaries is investigated in Paper I with respect to the nature of the boundary roughness, geometrical... (More)  In this thesis, theoretical studies of the transport properties of three nanoscale systems: onedimensional (1D) quantum wires (QWRs), zerodimensional (0D), laterally confined, doublebarrier resonant tunnelling structures (DBRTSs) and threeterminal ballistic junctions (TBJs), have been performed. In the first part of the thesis, an overview of the realization and properties of such systems is given along with a description of modelling tools used in the calculations. The second and main part of the thesis contains the original research results, summarized into seven papers.
The conductance of QWRs with corrugated boundaries is investigated in Paper I with respect to the nature of the boundary roughness, geometrical parameters of the QWR and temperature. It is shown that, due to the structural imperfections, the conductance exhibits rapid fluctuations, strong, broad dips between adjacent conductance plateaus at very low temperatures and, in general, a suppression of the conductance below the values expected for an ideal QWR. The results agree with existing experimental results.
Experimental studies of the transport properties of 0D quantum dots obtained by laterally confining vertical DBRTSs by means of metallic gates have shown complex, gatedependent fine structure in the measured currentvoltage (IV) characteristics. The origin of this fine structure is theoretically studied and explained (Papers IIV) in terms of quasi1D0D1D systems with a tunable lateral confinement. It is shown that, due to the low dimensionality of the emitter, dot and collector regions, complex fine structure, which is strongly dependent on Fermi energy, sourcedrain voltage, and gate voltage, is formed in the IV characteristics, which may explain the experimentally observed results. A tentative comparison between experiments and theory is made in Paper IV.
Threeterminal junction systems have very recently emerged as excellent candidates for use as building blocks in the formation of nanoscale electronic devices. A general formalism for the calculation of electron transport through three terminal quantum structures is presented in Paper VI. Using this method, the transport through Yshaped TBJ structures is studied in Paper VII. Quantum effects are shown to influence the transport properties of TBJs at low temperatures, possibly enabling new device functionality. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/record/465268
 author
 Csontos, Dan ^{LU}
 opponent

 Prof Büttiker, Markus, Département de Physique Théorique, Université de Genève
 organization
 publishing date
 2002
 type
 Thesis
 publication status
 published
 subject
 keywords
 ballistic transport, quantum wire, quantum dot, resonant tunnelling, threeterminal, disorder, Physics, Fysik, Fysicumarkivet A:2002:Csontos, scattering matrix, quantum transport
 pages
 154 pages
 publisher
 Division of Solid State Physics, Department of Physics, Lund University, Box 118, SE221 00 Lund, Sweden,
 defense location
 Lecture Hall B, Department of Physics, Lund University
 defense date
 20021129 13:15
 external identifiers

 Other:ISRN: LUFTD2/TFFF0064/164(2002)
 ISBN
 9162854607
 language
 English
 LU publication?
 yes
 id
 d3f233b3d7b5410faaed757237fa2bc0 (old id 465268)
 date added to LUP
 20070928 09:48:54
 date last changed
 20160919 08:45:03
@phdthesis{d3f233b3d7b5410faaed757237fa2bc0, abstract = {In this thesis, theoretical studies of the transport properties of three nanoscale systems: onedimensional (1D) quantum wires (QWRs), zerodimensional (0D), laterally confined, doublebarrier resonant tunnelling structures (DBRTSs) and threeterminal ballistic junctions (TBJs), have been performed. In the first part of the thesis, an overview of the realization and properties of such systems is given along with a description of modelling tools used in the calculations. The second and main part of the thesis contains the original research results, summarized into seven papers.<br/><br> <br/><br> The conductance of QWRs with corrugated boundaries is investigated in Paper I with respect to the nature of the boundary roughness, geometrical parameters of the QWR and temperature. It is shown that, due to the structural imperfections, the conductance exhibits rapid fluctuations, strong, broad dips between adjacent conductance plateaus at very low temperatures and, in general, a suppression of the conductance below the values expected for an ideal QWR. The results agree with existing experimental results.<br/><br> <br/><br> Experimental studies of the transport properties of 0D quantum dots obtained by laterally confining vertical DBRTSs by means of metallic gates have shown complex, gatedependent fine structure in the measured currentvoltage (IV) characteristics. The origin of this fine structure is theoretically studied and explained (Papers IIV) in terms of quasi1D0D1D systems with a tunable lateral confinement. It is shown that, due to the low dimensionality of the emitter, dot and collector regions, complex fine structure, which is strongly dependent on Fermi energy, sourcedrain voltage, and gate voltage, is formed in the IV characteristics, which may explain the experimentally observed results. A tentative comparison between experiments and theory is made in Paper IV.<br/><br> <br/><br> Threeterminal junction systems have very recently emerged as excellent candidates for use as building blocks in the formation of nanoscale electronic devices. A general formalism for the calculation of electron transport through three terminal quantum structures is presented in Paper VI. Using this method, the transport through Yshaped TBJ structures is studied in Paper VII. Quantum effects are shown to influence the transport properties of TBJs at low temperatures, possibly enabling new device functionality.}, author = {Csontos, Dan}, isbn = {9162854607}, keyword = {ballistic transport,quantum wire,quantum dot,resonant tunnelling,threeterminal,disorder,Physics,Fysik,Fysicumarkivet A:2002:Csontos,scattering matrix,quantum transport}, language = {eng}, pages = {154}, publisher = {Division of Solid State Physics, Department of Physics, Lund University, Box 118, SE221 00 Lund, Sweden,}, school = {Lund University}, title = {Modelling of Quantum Transport in Nanostructures}, year = {2002}, }