We investigate the magneto-transport properties of epitaxial graphene single-layer on 4H-SiC(0001), grown by atmospheric pressure graphitization in Ar, followed by H₂ intercalation. We directly demonstrate the importance of saturating the Si dangling bonds at the graphene/SiC(0001) interface to achieve high carrier mobility. Upon successful Si dangling bonds elimination, carrier mobility increases from 3 000 cm²V⁻¹s⁻¹ to >11 000 cm²V⁻¹s⁻¹ at 0.3 K. Additionally, graphene electron concentration tends to decrease from a few 10¹² cm⁻² to less than 10¹² cm⁻². For a typical large (30 × 280 μm²) Hall bar, we report the observation of the integer quantum Hall states at 0.3 K with well developed transversal resistance plateaus at Landau level filling factors of ν = 2, 6, 10, 14… 42 and Shubnikov de Haas oscillation of the longitudinal resistivity observed from about 1 T. In such a device, the Hall state quantization at ν = 2, at 19 T and 0.3 K, can be very robust: the dissipation in electronic transport can stay very low, with the longitudinal resistivity lower than 5 mΩ, for measurement currents as high as 250 μA. This is very promising in the view of an application in metrology.

We have investigated the energy loss of hot electrons in metallic graphene by means of GHz noise thermometry at liquid helium temperature. We observe the electronic temperature T$\propto${}V at low bias in agreement with the heat diffusion to the leads described by the Wiedemann-Franz law. We report on T$\propto${}V behavior at high bias, which corresponds to a T4 dependence of the cooling power. This is the signature of a 2D acoustic phonon cooling mechanism. From a heat equation analysis of the two regimes we extract accurate values of the electron-acoustic phonon coupling constant $\Sigma${} in monolayer graphene. Our measurements point to an important effect of lattice disorder in the reduction of $\Sigma${}, not yet considered by theory. Moreover, our study provides a strong and firm support to the rising field of graphene bolometric detectors.

The development of devices suitable for heat management requires materials whose thermal properties and synthesis are well controlled.