Based On The Wide Bandgap Semiconductor 4 H - Sic Power Igbt Model And Characteristics Of The Study

The physical properties of the wide band-gap semiconductor materials4hydrogen siliconcarbide(4H-SiC) are systematically studied, its physical parameters, such as, forbidden band-gapwidth Eg, carrier’s mobility μ, etc, are analyzed and calculated, its ionization rate theoreticalanalysis formula which will be used in devices models for calculation is fitted with itsmeasurement ionization rate curves reported in literatures. In order to compare the performancedifferences of power insulate gate bipolar transistors(IGBTs) based on wide band-gap material4H-SiC and silicon, we construct the4H-SiC IGBT models based on the basic theory ofsemiconductor physics and devices physics, for4H-SiC and silicon, its quantitative relationshipof carrier mobility with doping concentration, output I-V curves with devices design andfabrication parameters, the relationships of epilayer doping concentration, epilayer thickness,on-resistance and breakdown voltage, switching characteristics with material properties anddevices blocking voltage rating are all described in detail with our devices model. MATLABsoftware is used to calculate those above characteristics of devices, the calculation results shownthat, for given doping concentration, the carrier mobility of4H-SiC were lower than that of silicon,so its conducting output currents were also smaller than that of silicon in the same design rule ofsame chip area and same devices terminal bias conditions, for devices with breakdown voltage of2000V, the calculation results show that the epilayer doping concentration for4H-SiC is one orderof magnitude higher than that of silicon, while the epilayer thickness and correspondingon-resistance are only about15percent that of silicon, so our research indicates that the4H-SiCdevices will have higher epilayer doping concentration and smaller epilayer thickness as well aslower on-resistance, and these will lead the more fast turn-on and switching characteristics whencompared with that of silicon IGBTs. So the planar plane pn junction with infinite junction depthis the ideal condition to achieve maximum breakdown voltage, while the tendency for both theepilayer doping concentration’s decrease and thickness’s increase as the devices breakdownvoltage increases is the same in the actual pn junction no matter it is made with silicon or4H-SiCmaterials.