Simulations results of the field- and temperature-dependent electronic conductivity in β-SiC are reported. The calculations based on the Monte Carlo procedure, reveal a velocity overshoot above 100 kV/cm for a 1.0 μm device at 300 K with a characteristic response time of about 0.3 ps. The steady state velocity at 900 K is shown to be in excess of 107 cm/s. Frequency behaviour of the complex small signal mobility has also been calculated at different temperatures and biasing fields. The real part of the a.c. mobility exhibits a peak at frequencies close to the relaxation rates, provided the transient velocity for the corresponding bias field has an overshoot. Finally, it has been shown that with device down scaling, the a.c. mobilities can be appreciably reduced, and that the device electron velocities substantially lowered due to carrier injection at the cathode.