Because SiC does not have velocity overshooting behaviour, the current density of SiC metal-semiconductor field-effect transistors (MESFETs) is restricted by low drift velocity in the parasitic region between source and gate where the applied electric field is low. In addition, the extension of the depletion region toward the drain side at high drain voltages increases the effective channel length and, as a result, lowers the cut-off frequency due to the increased transit time.