Study Of 4H-SiC Merged PiN/Schottky(MPS) Diodes

4H-SiC MPS is a promising power semiconductor rectifier. The working mechanics, optimum design and power dissipation was studied in this thesis.The transport characteristics of 4H-SiC MPS was simulated. The working mechanics of 4H-SiC MPS was two-dimensional analyzed. According to the analysis of physical quantities in the body, we got a conclusion that the effect of PN junction on Schottky is through its depletion layer and the gap between two PN junctions. The application of MPS structure improves the reverse characteristics and preserves the forward characteristics of SBD. And the application of Silicon carbide enhances the advantage of MPS structure.A analytical model of 4H-SiC MPS was given. Based on this model, it was presented that how to select the thickness of epilayer, the doping concentration of epilayer, Schottky contact, the width of PN grid, the depth of PN junction and the doping concentration of PN junction for the trade-off between forward and reverse characteristics. It also put forward that how to select appropriate epilayer doping concentration and thickness, PN junction depth and JTE technology to increase the breakdown voltage of 4H-SiC MPS.A power dissipation model of 4H-SiC MPS was established. The power dissipation of 4H-SiC MPS was calculated. The influences of temperature on SiC mobility, ionization rate and intrinsic carriers density were taken into account. We found that the 4H-SiC MPS has an optimal work temperature. For the MPS mentioned in this paper, the lowest power dissipation emerges at about 770K.