Exclusion principle and theLandauer-Buttiker formalism The Landauer-Buttiker formalism has been very successful in describingelectronic. Landauer-Büttiker formalism. Calculation of the electronic current flowing through a system due to application of external bias voltage is one of the most difficult. Landauer-Büttiker formalism. Examples. Farkas Dániel Gergely. Msc physics student. 1. Contents. Difference of potencials; Difference of temperatures.
|Published (Last):||27 January 2012|
|PDF File Size:||6.57 Mb|
|ePub File Size:||5.38 Mb|
|Price:||Free* [*Free Regsitration Required]|
Some kinds of scattering can only cause a change in electron lzndauer, others can cause energy loss. Phenomena like double-slit interferencespatial resonance and other optical or microwave -like effects could be exploited in electronic systems at nanoscale in systems including nanowires and nanotubes.
Over a limited distance, the electron wave function will remain coherent. Information about the state of the electrons at the input is then lost. The contacts have a multiplicity of modes due to their larger size in comparison to the channel. The widely encountered phenomenon of electrical contact resistance or ECR, arises as an electric current flowing through a rough interface is restricted to a limited number of contact spots.
Conversely, the quantum confinement in the 1D GNR channel constricts the number of modes to carrier degeneracy and restrictions from the energy dispersion relationship and the Brillouin zone.
Transport becomes statistical and stochastic. There are also other scattering mechanisms which apply to different carriers that are not considered here e.
Ballistic conduction – Wikipedia
When the radius of a contact spot is larger than the mean free path of electrons, the contact resistance can be treated classically. This page was last edited on 19 Decemberat Ballistic transport is observed when the mean free path of the electron formaism much longer than the dimension of the medium through which the electron travels. Ballistic conduction differs from superconductivity due to the absence of the Meissner effect in the material.
Views Read Edit View history. InRolf Landauer proposed that conduction in a 1D system could be viewed as a transmission problem.
Phys. Rev. B 45, () – Exclusion principle and the Landauer-B\”uttiker formalism
For the 1D graphene nanoribbon field effect transistor GNR-FET on the right where the channel is assumed to be ballisticthe current from A to B, given by the Boltzmann transport equationis. Ballistic conduction is the unimpeded flow of charge, or energy-carrying particles, over relatively long distances in a material.
Heat conduction can experience ballistic thermal transport when heating size is larger than phonon mean free paths. March Learn formalixm and when to remove this template message. From Wikipedia, the free encyclopedia. Articles needing cleanup from March All pages needing cleanup Cleanup fornalism articles with a reason field from March Wikipedia pages needing cleanup from March All articles with unsourced statements Articles with unsourced statements from July Articles with unsourced statements from June Articles with unsourced statements from February Such a transport regime has been found to depend on the nanoribbon edge structure and the electron energy.
Electrons have several properties: Their ballisticity is nearly 0. See List of thermal conductivities. A comparison with light provides rormalism analogy between ballistic and non-ballistic conduction.
The landaher problem is: Since the contacts and the GNR channel are connected by leads, the transmission probability is smaller at contacts A and B.
Electronic Transport in Mesoscopic Systems. This is because there is an energy to be paid to extract the electron from the medium work function. There are major differences between carbon nanotubes which are hollow and Si nanowires which are solid. Electrical contacts resulting in ballistic electron conduction are known as Sharvin Contacts. Consider a coherent source of electrons connected to a conductor.
For example, ballistic transport can be observed in a metal nanowire: A ballistic conductor would stop conducting if the driving force is turned off, whereas in a superconductor current would continue to flow after the driving supply is disconnected. But there is still almost no energy loss. You still can deterministically predict its behavior and use it for computation theoretically. Thus, ballistic transport in a material is determined by how ballistically conductive that material is. Non-ballistic electrons behave like light diffused in milk or reflected off a white wall or a piece of paper.
Ballistic conduction is typically observed in quasi-1D structures, such as carbon nanotubes or silicon nanowiresbecause of extreme size quantization effects in these materials.
Electrons can be scattered several ways in a conductor. For example, electrons in carbon nanotubes have two intervalley modes and two formalissm modes. The electron alters its motion only upon collision with the walls.
If the electrons undergo inelastic interactions too, they lose energy and the result is a second mechanism of resistance. Ballistic thermal transport has been observed in ubttiker materials systems . Retrieved from ” https: From the resistance point of view, stochastic not oriented movement of electrons is useless even if they carry the same energy — they move thermally.
To get these characteristic scattering rates, one would need to derive a Hamiltonian and solve Fermi’s golden rule for the system in question.
However it is still possible to observe ballistic conduction in Si nanowires at very low temperatures 2—3 K. Ballistic transport is coherent in wave mechanics terms.