PhD Abstract

The future International System of Units, based on fundamental constants, will allow to take full advantage of the quantum standards of resistance, current and voltage that are linked to the planck constant and the elementary charge only. In this thesis, we have developed and studied a resistance standard based on the quantum Hall effect in graphene obtained by chemical vapor deposition (propane/hydrogen) on silicon carbide substrate. For the first time we were able to show that a graphene resistance standard could operate at more practical experimental conditions than its counterpart in GaAs/AlGaAs, ie at higher temperatures (T = 10 K), weaker magnetics fields (B = 3,5 T) and larger measurement currents (I = 500 μA). From an understanding and improvement perspective, we have analyzed the fabrication process of the Hall bar and its reproducibility, tested a method to modify the electronic density, and investigated the quantum Hall effect dissipation mechanisms. In a second part, we have demonstrated that it was possible to realize a programmable and versatile quantum current source from the elementary charge, by combining the two quantum standards of voltage and resistance in a quantum circuit integrating a cryogenic current comparator. Currents were generated in the range from 1 μA to 5 mA, with a relative uncertainty never achieved before of 10⁻⁸. We have also showed that this current standard, realizing the new definition of the ampere, could be used to calibrate an ammeter.

Key words

metrology, quantum Hall effect