A MOS-driver Compatible JFET Structure with Enhanced Gate Source Characteristics

Reference #: 00780

This invention is a modified Junction Field Effect Transistor (JFET) gate structure that allows the gate to be driven by a conventional Metal Oxide Semiconductor Field Effect Transistor (MOSFET) gate driver. Prior-art JFETs have different gating requirements from MOSFETs because of the diode between gate and source. This invention reduces the amplitude of the gate current needed to control the device because in the present invention the gate current is a unipolar current (only one carrier type), rather than a bipolar current (both carrier types) as in a conventional JFET. The gate-source and gate-drain capacitances of JFET in the present invention are reduced significantly because the gate-source and gate-drain depletion width are much larger than those in conventional JFET. Reduced gate-source and gate-drain capacitances significantly improve dynamic performance of SiC JFET.

This invention for improves the performance of silicon carbide (SiC) JFETs, but the invention is also applicable to JFETs using other semiconductor materials, such as silicon (Si) or gallium nitride (GaN). This new gate structure can be applied to any JFET structure, including but not limited to vertical JFET and planar JFET, Si JFET and SiC JFET, normally on JFET, and normally off JFET.

• Only one carrier type can penetrate both junctions between n gate region and n channel region 22, which reduces gate current significantly.

• Gate-source capacitance and gate-drain capacitance are reduced significantly because the depletion width between n gate region 24 and source region and the depletion width between gate region 24 and drain region are increased significantly

• Reduced capacitance between gate region 24 and channel region and between gate region 24 and drift region can improve dynamic performance of JFET significantly.