Ref HAL: hal-03037516_v1
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We report on measurements in large quantum Hall devices, made of high-quality graphene grown by propane/hydrogen chemical vapor deposition on SiC. These devices, having all the properties of an ideal quantum electrical resistance standard, surpass state-of-the-art GaAs/AlGaAs devices by considerable margins in their operational conditions. The Hall resistance can be found accurately quantized within one part in 10(9) over a 10-T range of magnetic fields with a lower bound at 3.5 T, temperatures as high as 10 K, or currents as high as 0.5 mA. This simplification sets the superiority of graphene for accessible and low-cost primary resistance standards.

Commentaires: Conference on Precision Electromagnetic Measurements (CPEM), Natl Res Council, Ottawa, CANADA, JUL 10-15, 2016

Ref HAL: hal-01932679_v1
DOI: 10.1109/IRMMW-THz.2016.7758889
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We report on THz emission from HgCdTe bulk films. Our experiments clearly show magnetically tunable THz emission that can be attributed to electron radiative recombination between the Landau levels (cyclotron emission). Energy band structure theoretical calculations using Kane Hamiltonian are performed. They allow identification of observed resonances as related to transitions between two lowest conduction band Landau levels.

Ref HAL: hal-01932629_v1
DOI: 10.1109/IRMMW-THz.2016.7758790
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We report on the first THz magnetospectroscopy of double HgTe quantum well in magnetic fields up to 16 T. Very recently, specific metal phase, which holds some properties of natural bilayer graphene, was predicted in this system. In this work, we focus on the double HgTe QW with parameters, corresponding to such `bilayer graphene' phase. In our experiments we clearly observe THz optical transitions from double-degenerated zero-mode Landau level. A good agreement between experimental and theoretical transition energies confirms previous prediction of `bilayer graphene' phase in double HgTe quantum wells.

Ref HAL: hal-01617109_v1
DOI: 10.1109/CPEM.2016.7540650
Exporter : BibTex | endNote
Résumé:

We report on measurements in large quantum Hall devices, made of high-quality graphene grown by propane/hydrogen chemical vapor deposition on SiC. These devices, having all the properties of an ideal quantum electrical resistance standard, surpass state-of-the-art GaAs/AlGaAs devices by considerable margins in their operational conditions. The Hall resistance can be found accurately quantized within one part in 109 over a 10-T range of magnetic fields with a lower bound at 3.5 T, temperatures as high as 10 K, or currents as high as 0.5 mA. This simplification sets the superiority of graphene for accessible and low-cost primary resistance standards.

Ref HAL: hal-01510409_v1
WoS: WOS:000391406200555
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1 Citation
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We device plasmonic, bolometric and thermoelectric antenna-coupled Terahertz photodetectors based on black phosphorus and hybrid van der Walls heterostructures, showing 20000 signal to noise ratios and 100pW/Hz1/2 noise equivalent powers in the 0.3-3 THz frequency range.

Ref HAL: hal-01939530_v1
Ref Arxiv: 1611.08179
DOI: 10.1103/PhysRevLett.117.237702
WoS: WOS:000389032600014
Ref. & Cit.: NASA ADS
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12 Citations
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We report on the stability of the quantum Hall plateau in wide Hall bars made from a chemically gated graphene film grown on SiC. The ν=2 quantized plateau appears from fields B≃5  T and persists up to B≃80  T. At high current density, in the breakdown regime, the longitudinal resistance oscillates with a 1/B periodicity and an anomalous phase, which we relate to the presence of additional electron reservoirs. The high field experimental data suggest that these reservoirs induce a continuous increase of the carrier density up to the highest available magnetic field, thus enlarging the quantum plateaus. These in-plane inhomogeneities, in the form of high carrier density graphene pockets, modulate the quantum Hall effect breakdown and decrease the breakdown current.

Ref HAL: hal-01417831_v1
DOI: 10.1002/pssc.201510264
WoS: WOS:000387954400031
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1 Citation
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We have found the possibility to probe the magnetic field-driven topological phase transition in HgTe-based transistors by measuring their Terahertz photoconductivity response. At the critical magnetic field to which zero-mode Landau levels cross, we have observed a pronounced photoconductivity peak independent on incident frequency and carrier concentration. Our results pave the way towards terahertz topological field effect transistors.