Investigation of SiC MOSFET’s current hump mechanism induced by false turn-on of the high-side body diode

Abstract

SiC MOSFETs have been widely used in high-frequency applications due to their high-speed switching characteristics. However, as the switching speed increases, the di/dt of the device also increases, which is highly influenced by the parasitic inductance created by the wire bonding and the package leads. In the half-bridge inductive switching structure, while the false turn-on mechanism of the switching device is well established, the displacement current flows in the high side device, operating in freewheeling mode through the body diode, has not been identified. In this paper, the current hump phenomenon of the SiC MOSFETs, caused by the high side MOSFET’s false turn-on during the low side turn-on transient in a half-bridge circuit, was analyzed. In addition, the effect of the high-side MOSFET’s false turn-on dependence under different parasitic inductance and load current level was analyzed. Double pulse tests were used to confirm the false turn-on phenomenon due to the parasitic inductance, and Sentaurus TCAD simulation was used to analyze the internal behavior of the device.