Robust quantum Hall resistance standard from uniform wafer-scale epitaxial graphene on SiC

We report high-precision resistance measurements on quantum Hall resistance devices fabricated from uniform epitaxial graphene grown by propane-hydrogen chemical vapor deposition on a two-inch silicon carbide substrate. Through molecular doping, we achieve a low carrier density regime (n_ s < 1.5 10¹¹ cm⁻²) combined with high mobility (≥ 6000 cm² V⁻¹ s⁻¹) at low temperature. Accurate quantization of the Hall resistance is demonstrated at magnetic flux densities as low as 3.5 T, temperatures up to 8 K, and measurement currents up to 325 A, with relative measurement uncertainties of a few parts per billion. A stability diagram mapping dissipation as a function of temperature and current provides insight into optimal doping conditions that maximize the breakdown current. All measurements were carried out in a pulse-tube-based cryomagnetic system, enabling simplified and continuous operation of the quantum Hall resistance standard without liquid helium consumption.