A normally-off type 5 kV class 4H-SiC JFET with low specific on-resistance, called SEJFET (Static Expansion channel JFET), has been fabricated. Its normally-off operation is realized at the temperature from RT to 600 K. A very fast switching time of the 4H-SiC SEJFET are realized. The turn-on time at RT is 20ns and the turn-off time at RT is 47ns. In this SEJFET, temperature dependences of the output characteristics and transfer characteristics are evaluated. Its specific on-resistance has a large positive temperature dependence, and its transconductance has a large negative temperature dependence. SiCJFET SEJFET

kV 600 A 4H-SiC flat package type pn diodes have been developed and their reverse recovery characteristics have been investigated. In spite of pn junction diodes, the developed diodes have a short reverse recovery time of 0.153 µs at room temperature. This diodes have 1/10th lower recovery loss and 1/3rd lower recovery time than those of a commercialized 2.5 kV Si diode in spite of high blocking voltage. When this diodes apply to PWM inverter, the carrier frequency that on-state loss is equal to switching loss is 1.45 times the Si diode's frequency at 398 K. By using the developed diode, high voltage high frequency inverter operation can be realized.SiC pn

A Novel 4H-SiC SEMOSFET (Static channel Expansion MOSFET) was developed. This SEMOSFET has buried gate in addition to MOS gate. By applying a buried gate voltage of less than built-in potential, its channel can be expanded and low specific on resistance was realized. Developed 4H-SiC SEMOSFET has a high performances, such as high blocking voltage, BV, of 5020 V, low specific on-resistance, "RonS" of 88 mΩcm 2 and switching speed of less than 35 ns. In all reported FETs with MOS structure, the SEMOSFET has the best trade-off between RonS and BV and the largest figure of merit of 286 MW/cm 2. Its RonS is about 1/140th that of the theoretical limit of Si MOSFET for this BV.

A normally-off type 5.3 kV 4H-SiC JFET with low specific on-resistance, called SEJFET (Static Expansion channel JFET), has been fabricated. Its normally-off operation was realized by a thin regrown epitaxial channel layer and using the buried p+ regions as a gate in addition to the top p+ regions. The achieved blocking voltage is the highest class BV among the reported SiC JFET. In a 5.3 kV 4H-SiC SEJFET, the lowest specific on resistance of 69 mΩcm 2 .Furthermore, the highest current capability among SiC JFET of 3.3 A is achieved. In all reported FETs, the SEJFET has the best trade-off between RonS and blocking voltage (BV), which is about 1/230 th lower than theoretical limit of a Si FET. Furthermore, the figure of merit (BV 2 /RonS) is 407 MW/cm 2 , and this value is the highest among reported normally off SiC FETs.SiC JFET SEJFET

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