Physics of Bipolar, Unipolar and Intermediate Conduction Modes in Silicon Carbide MOSFET Body Diodes

This paper details the device physics of Silicon Carbide MOSFETs in third quadrant operation. It is observed that the gate bias has a large effect on controlling the injection efficiency at the anode of the body diode. The change in threshold voltage due to body-effect and the voltage drop across the anode junction play a key role in controlling the balance between electron and hole currents at the anode end, which gives the device the capability to operate in unipolar, bipolar or intermediate conduction modes depending on current density and operating temperature.