The Monte Carlo method is used to simulate electron transport in bulk würtzite phases of 6H-SiC and 4H-SiC using a three valley analytical band structure. Spherical, non-parabolic conduction band valleys at the , K and U symmetry points of the Brillouin zone are fitted to the first-principles band structure. The electron drift velocity is calculated as a function of temperature and ionized donor concentration in the ranges of 300-600 K and 1016-1020 cm-3, respectively. Due to the freezout of deep donor levels the role of ionized impurity scattering in 6H-SiC is suppressed and the role of phonon scattering is enhanced, compared to 4H-SiC. For two materials, it is found that electron velocity overshoot only occurs when the electric field is increased to a value above a certain field unique to each material. This critical field is strongly dependent on the material parameters.

Keywords