▎ 摘　　要

We report the phase space defined by the quantum Hall effect breakdown in polymer gated epitaxial graphene on SiC (SiC/G) as a function of temperature, current, carrier density, and magnetic fields up to 30 T. At 2 K, breakdown currents (I-c) almost 2 orders of magnitude greater than in GaAs devices are observed. The phase boundary of the dissipationless state (rho(xx) = 0) shows a [1 - (T/T-c)(2)] dependence and persists up to T-c > 45 K at 29 T. With magnetic field Ic was found to increase alpha B-3/2 and T-c alpha B-2. As the Fermi energy approaches the Dirac point, the nu = 2 quantized Hall plateau appears continuously from fields as low as 1 T up to at least 19 T due to a strong magnetic field dependence of the carrier density.