Design And Characteristic Simulation Of SiC Vertical Power MOSFET

SiC vertical power MOSFETs are one of the most attractive item in electric power device field.Two kind of SiC vertical power MOSFETs——VDMOS and UMOS,were designed on the base of the theory of power device,and some simulation had been taken by using ISE TCAD 7.0.For VDMOS,by using 6H-SiC and 4H-SiC separately as substrate material, compared and studied their difference, and the result indicated that the drain current of 4H-SiC VDMOS is 1.5 times higher than those of 6H-SiC VDMOS, when Vgs is 8V.It validated that the saturation current density of 4H-SiC devices is higher than 6H-SiC devices, this due to the higher body mobility of 4H-SiC and suffers less effect of quasi-saturation.By analyzing the switching time and switching loss per unit area of devices,make clear that 4H-SiC is more suit for using in power VDMOS devices.Then analysed the effect of thickness of gate oxide layer and channel length on the characteristic of SiC VDMOS, The analyse of threshold voltage and drain current,indicate that the threshold voltage increase with the increase of the thickness of gate oxide layer or channel length.and that the drain current decrease with the increase of the thickness of gate oxide layer or channel length.For 4H-SiC UMOS,first analysed the basic characteristic of device,which proved it have good control ability of gate,and have higher breakdown voltage.Then analysed the effect of thickness of gate oxide layer and the doping concentration of P base on transfer character,the result indicate that threshold increase with the increase of the thickness of gate oxide layer or the doping concentration of P base.furthermore,their mechanism were discussed.The research work of this paper have significance for optimize design of SiC vertical power MOSFET.