In mesoscopic physics, a quantum wire is an electrically conducting wire in which quantum effects influence the transport properties. Usually such effects appear in the dimension of nanometers, so they are also referred to as nanowires.
If the diameter of a wire is sufficiently small, electrons will experience quantum confinement in the transverse direction. As a result, their transverse energy will be limited to a series of discrete values. One consequence of this quantization is that the classical formula for calculating the electrical resistance of a wire,
is not valid for quantum wires (where is the material's resistivity, is the length, and is the cross-sectional area of the wire).
Instead, an exact calculation of the transverse energies of the confined electrons has to be performed to calculate a wire's resistance. Following from the quantization of electron energy, the electrical conductance (the inverse of the resistance) is found to be quantized in multiples of , where is the electron charge and is the Planck constant. The factor of two arises from spin degeneracy. A single ballistic quantum channel (i.e. with no internal scattering) has a conductance equal to this quantum of conductance. The conductance is lower than this value in the presence of internal scattering.
The importance of the quantization is inversely proportional to the diameter of the nanowire for a given material. From material to material, it is dependent on the electronic properties, especially on the effective mass of the electrons. Physically, this means that it will depend on how conduction electrons interact with the atoms within a given material. In practice, semiconductors can show clear conductance quantization for large wire transverse dimensions (~100 nm) because the electronic modes due to confinement are spatially extended. As a result, their Fermi wavelengths are large and thus they have low energy separations. This means that they can only be resolved at cryogenic temperatures (within a few degrees of absolute zero) where the thermal energy is lower than the inter-mode energy separation.
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This lecture overviews and discusses the last trends in the technology and principles of nanoelectronic devices for more aggressive scaling, better performances, added functionalities and lower energy
In mesoscopic physics, a quantum wire is an electrically conducting wire in which quantum effects influence the transport properties. Usually such effects appear in the dimension of nanometers, so they are also referred to as nanowires. If the diameter of a wire is sufficiently small, electrons will experience quantum confinement in the transverse direction. As a result, their transverse energy will be limited to a series of discrete values.
Une boîte quantique ou point quantique, aussi connu sous son appellation anglophone de quantum dot, est une nanostructure de semi-conducteurs. De par sa taille et ses caractéristiques, elle se comporte comme un puits de potentiel qui confine les électrons (et les trous) dans les trois dimensions de l'espace, dans une région d'une taille de l'ordre de la longueur d'onde des électrons (longueur d'onde de De Broglie), soit quelques dizaines de nanomètres dans un semi-conducteur.
Déplacez-vous dans les propriétés nanométriques, en mettant l'accent sur les effets de surface et les phénomènes quantiques, la quantification de la conductance et la microscopie par sonde à balayage.
Déplacez-vous dans des propriétés nanométriques, mettant l'accent sur les effets de surface et les phénomènes quantiques, explorant des propriétés électroniques, mécaniques, magnétiques, photoniques et chimiques uniques à l'échelle nanométrique.
The properties of semiconductors heterostructures of nanoscopic dimensions change from that of bulk material according to the rules of quantum mechanics. The planar quantum wells (QWs) are widely used
Novel light-emitting devices and micro-optical-circuit elements will rely upon understanding and control of light-matter interaction at the nanoscale. Recent advances in nanofabrication and micro-proc
Semiconductor quantum wires (QWRs) and quantum dots (QDs) are nanoscale heterostructures, which form fascinating low-dimensional systems for fundamental studies of quantum-mechanical effects and are a