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):||7 May 2012|
|PDF File Size:||7.38 Mb|
|ePub File Size:||12.84 Mb|
|Price:||Free* [*Free Regsitration Required]|
Ballistic transport is coherent in wave mechanics terms. The size and distribution of these contact spots is governed by the topological structures of the contacting surfaces forming the lxndauer contact. For the 1D graphene nanoribbon field effect transistor GNR-FET on the right where the channel is assumed to be ballisticthe current from A buttikfr B, given by the Boltzmann transport equationis.
It is often incorrectly thought that Si nanowires are quantum confined ballistic conductors.
Like monochromatic light passing through milk, electrons undergo elastic interactions. Consider a coherent source of electrons connected to a conductor.
Ballistic transport is observed when the mean free fogmalism of the electron is much longer than the dimension of the medium through which the electron travels. For example, electrons in carbon nanotubes have two intervalley modes and two spin modes. Transport becomes statistical and stochastic. Retrieved forjalism ” https: 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.
This article may require cleanup to meet Wikipedia’s quality standards.
Ballistic conduction – Wikipedia
See List of thermal conductivities. Ballistic thermal transport has been observed in multiple formmalism systems . Ballistic conduction is typically observed in quasi-1D structures, such as carbon nanotubes or silicon nanowiresbecause of extreme size quantization effects in these materials.
Over a limited distance, the electron wave function will remain coherent. March Learn how and when to remove this template message. Ballistic conduction differs from superconductivity due to the absence of the Landaeur effect in the material.
In mesoscopic physicsBallistic conduction ballistic transport is the transport of charge carriers in a medium usually electronshaving negligible electrical resistivity caused by scattering. It is theoretically possible for ballistic conduction to be extended to other quasi-particles, but this has not been experimentally verified. Nanoelectronics Charge carriers Mesoscopic physics. From Wikipedia, the free encyclopedia. You still can deterministically predict its behavior and use it for computation theoretically.
Their ballisticity is nearly 0. A comparison with light provides an analogy between ballistic and non-ballistic conduction. The dominant scattering mechanism at room temperature is that of electrons emitting optical phonons.
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. Some kinds of scattering can only cause a change in electron direction, others can cause energy loss.
As mentioned, nanostructures such as carbon nanotubes or graphene nanoribbons are often considered ballistic, but these devices only very closely resemble ballistic conduction. Normally, transport of electrons or holes is dominated by scattering events, which relax the carrier momentum in an effort to bring the conducting material to equilibrium.
However it is still possible to observe ballistic conduction in Si nanowires at very low temperatures 2—3 K. Buttikre get these characteristic scattering rates, one would need to derive a Hamiltonian and solve Fermi’s golden rule for the system in question. This is because there is an energy to be paid to extract the electron from the medium work function. Views Read Edit View history. Non-ballistic electrons behave like light diffused in milk or reflected off a white lansauer or a piece of paper.
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. The mean free path can be increased by reducing the number formalims impurities in a crystal or by lowering its temperature. InRolf Landauer proposed that conduction in a 1D system could be viewed as a transmission problem. Heat conduction can experience ballistic thermal transport when heating size is larger than phonon mean free paths.
For a given particle, a mean free path can be described as being the average length that the electron can travel freely, i. Therefore, even in the case of a perfect ballistic transport, there is a fundamental ballistic conductance which saturates the current of the device with a resistance of approximately Electrons which undergo inelastic interaction are then similar to non-monochromatic light.
Phys. Rev. B 45, () – Exclusion principle and the Landauer-B\”uttiker formalism
From the resistance point of view, stochastic not oriented movement of electrons is useless even if they carry the same energy — they move thermally.
The specific problem is: Isotopically pure diamond can have a significantly higher thermal conductivity. 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 Such a transport regime has been found to depend on the nanoribbon edge structure and the electron energy.
Articles needing cleanup from March All pages needing cleanup Cleanup tagged 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 In terms of scattering mechanisms, optical phonon emission normally dominates, depending on the material and transport conditions. In particular, for surfaces with high fractal dimension contact spots may be very small.