First experimental test on bipolar mode field effect transistor prototype in 4H-SIC: A proof of concept

In this paper the Bipolar Mode Field Effect Transistor (BMFET) is demonstrated for the first time in 4H-SiC. The structure is based by two p+-type regions symmetrically placed at both sides of a n-type region channel and the device implements two control mechanisms: into the channel the potential barrier controls the electron flow in the off-state operations, like VJFET-based devices, whereas, during the on-state, the holes injected from the p-n junctions induce the conductivity modulation of the channel reducing the on-resistance with beneficial effects on current gain and switching operations. In order to avoid the reduction of carrier lifetime into the channel due to ion implantation and trench etching, an ad-hoc fabrication process has been set-up to enable the conductivity modulation into the channel. First experimental tests on the prototypes show the correct operations of the device as demonstrated from the changing of the output characteristic from triode-like to pentode-like behaviors, which are ascribed to the two main operation principles of the device.