Research On4H-SiC SJ JBS With Ultra Low Leakage Current

High voltage high power4H-SiC SBD (Schottky barrier diode) is simulated and analyzed using two dimensional device simulator ISE-TCAD in this paper. In this research, in order to reduce the reverse leakage current, specific on-resistance and breakdown voltage, the forward and reverse characteristics of4H-SiC Schottky barrier diode and Junction barrier schottky are analyzed. Then novel device structure is proposed. The newly device not only breaks throuth the limitation of SiC material, but it can also achieve extreme low leakage current. Finally, the paper answers the question why there is high frequency oscillation in the high power SiC schottky diode in the IGBT module.The paper mainly analyzes transport mechanism of the leakage current of the4H-SiC schottky barrier diode and provides a simple model. Then the SJ(Super Junction)structure which can break throuth the limitation of SiC material is introduced and realized in SBD. So the namely SJ SBD is born. Then the effect of the SJ structure parameter on the reverse leakage current, specific on-resistance and breakdown voltage of SJ SBD is simulated and analyzed. The study results show that the SJ structure can not shield the high electric field away from the Schottky contact. But it can achieve low leakage current due to its electric field modulation effect. In order to further reduce the leakage current of SiC SBD, a novel SiC SBD-SJ JBS (Super Junction Junction Barrier Schottky) is proposed in this paper. Then the effect of the key SJ JBS structure parameters on the he reverse leakage current, specific on-resistance and breakdown voltage of this diode is simulated and analyzed. The study results show that The SiC SJ JBS not only breaks throuth the limitation of SiC material, but it can also achieve extreme low leakage current. Its leakage current can be as low as9.2×10-8A/cm2under a reverse voltage as high as2273V. So far in theory, the leakage current is the lowest one that the SiC SBD can achieve under a reverse voltage higher than2000V. And then the reverse recovery characteristics of the SiC SJ JBS is studied. The SiC SJ JBS show superior reverse recovery performance. Lastly, the paper explain why there is high frequency oscillation in the high power SiC schottky diode in the IGBT module.