  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 cm^2/Vs to > 11 000 cm^2/Vs at 0.3 K.
Additionally, graphene electron concentration tends to decrease from a few
10^12 cm^-2 to less than 10^12 cm^-2. For a typical large (30x280 um^2) 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 fillings factors
of nu = 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 nu=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 mOhm, for measurement currents as high as 250 uA. This is very promising
in the view of an application in metrology.
