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Métrologie quantique
(3) Production(s) de l'année 2019
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Electrochemical Capacitance and Transit Time in Quantum Hall Conductors 
Auteur(s): Delgard A., Chenaud B., Mailly Dominique, Gennser Ulf, Ikushima Kenji, Chaubet C.
(Article) Publié:
Physica Status Solidi B, vol. p.1800548 (2019)
Ref HAL: hal-02137172_v1
DOI: 10.1002/pssb.201800548
WoS: 000473612400011
Exporter : BibTex | endNote
Résumé: In a two dimensional electron gas, low energy transport in presence of a magnetic field occurs in chiral 1D channels located on the edge of the sample. In the AC description of quantum transport, the emittance determines the amplitude of the imaginary part of the admittance, whose sign and physical meaning are determined by the sample topology: a Hall bar is inductive while a Corbino ring is capacitive. In this article, the perfect capacitive character of Corbino samples in the quantum Hall effect regime is shown. A vanishing conductance and an electrochemical capacitance which depends on the density of states of 1D channels are measured. Our samples have no gate, neither on the side nor on the top, and the inner capacitances are measured. The transit time of electrons across the device is obtained and the drift velocity of carriers is deduced.
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Magnetic-TEGFET: Transistor Without a Gate
Auteur(s): Raymond A., Chaubet C., Delgard A., Chenaud B., Cavanna Antonella, Harmand Jean Christophe, Zawadzki Wlodzimierz
(Article) Publié:
Physica Status Solidi B, vol. p.1800509 (2019)
Ref HAL: hal-02137158_v1
DOI: 10.1002/pssb.201800509
WoS: 000473612400001
Exporter : BibTex | endNote
Résumé: Low‐temperature current–voltage characteristics of n‐type GaAs/GaAlAs quantum wells delta‐doped in GaAs channel with Be acceptors are studied in the presence of a magnetic field. Negatively charged acceptor ions localize 2D conduction electrons by a combined effect of a quantum well and magnetic field parallel to the growth direction. In acceptor‐doped samples, the Hall electric field plays the role of the gate voltage. It is shown that at magnetic fields as weak as 1.5 T (or higher), the drain current reaches a constant value independent of the drain voltage. This phenomenon is due to the electron localization resulting in the decrease of conducting electron density in the crossed‐field configuration. The above special behavior of acceptor‐doped GaAs/GaAlAs heterostructures is exploited to realize a device called Magnetic‐TEGFET (Magnetic Two‐dimensional Electron Gas Field Effect Transistor) operating at low temperatures. The elimination of the gate in the studied transistor suppresses the gate‐to‐drain leakage current, which, in the standard TEGFETs, results in the electronic shot noise.
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Transistor Magnétique à effet de champ à gaz d’électrons bidimensionnel, dispositif et procédé associés
Auteur(s): Raymond A., Chaubet C.
Brevet: #WO2019002453A1, (2019)
Ref HAL: hal-01705324_v1
Exporter : BibTex | endNote
Résumé: le M-TEGFET, est un nouveau type de transistor, sans grille, fonctionnant grâce à un effet magnétique.
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