Industrial feasibility test of a graphene-enabled turnkey quantum resistance system

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Benchmark: The minimum requirement for primary resistance metrology is to measure the quantum Hall resistance to better than 1 part per billion (or 1 nanoOhm/Ohm). When using traditional GaAs/AlGaAs heterostructues or Si MOSFETs this requires a measurement current of at least 25 microamps through the device without breakdown of the quantum Hall effect. To achieve this the temperature must be below 1 kelvin and the magnetic field around 10 tesla or higher to achieve robust Landau quantisation. Benefit of graphene: Graphene improves on this in several ways: firstly the Landau quantisation is intrinsically much stronger (factor of 5 at 10 T). Secondly, because of the specific phonon spectrum and electron-phonon coupling strength the relaxation of hot carriers in graphene is 10 times faster than in GaAs, resulting in a much larger breakdown current. The combination of these two unique graphene properties mean that a superior quantum Hall resistance can be constructed. However, so far these effects have been demonstrated in academic research and the advanced laboratory conditions at the National Physical Laboratory. Targetted improvement: The challenge of this project to take these results forwards and make these measurements routine in a simple turn-key cryogen-free magneto-transport system. Specifically the project needs to address the noise levels produced in cryogen-free pulse-tube coolers, the control of the charge carrier density and homogeneity at very low carrier densities, and ability to perform ppb-level measurements outside metrology laboratory.