Modeling And Simulation Of SiC Super Junction Power Switching Diode

With the development of high frequency in power electronics, power switching diodesneed to have better electric properties, including low forward voltage drop, small reversecurrent, short recovery time, low on resistance and fast reverse recovery. Because silicon islimited by its crystal structure, the conventional structure of silicon device can not met thedemands of people. The narrow silicon band gap, relatively low thermal conductivity and lowcritical breakdown voltage make the development of silicon power device have certainlimitation, which is named silicon limits.The silicon carbide material has excellent performance in meeting the demands ofhigh-temperature, high current and intense radiation environments. So silicon carbidematerials are widely used as a typical representative of the third generation of WBGsemiconductor materials. The silicon carbide with high thermal conductivity, high electronicvelocity saturation and high critical breakdown voltage, is the first “successor” in the field ofpower semiconductor silicon materials. So people create Super Junction structure.Super Junction structure is made up of drift region, which is constituted by means ofhigher concentrations of n-Zone and p-Zone staggering to replace each other at the soft dopedzone, N+-Zone above the pressure bearing layer and P+-Zone under the pressure bearing layer.The pressure bearing layer and p-Zone mingle in SJ structure. Thus, excess current charge canbe neutralized. Add reverse voltage to the drift region and the electric-field in horizontaldirection will be produced. The electric field will make electron hole spread from p-Zone ton-Zone and make electron spread from n-Zone to p-Zone. When the interaction between p-Zone and n-Zone makes the electric charge balanced, the drift layer will be evenly exhausted.At that time, the electric field is evenly distributed, though which the breakdown voltage VBof pressure bearing layer can be improved. The conduction resistance RONalso greatlyreduced by using the high n type doping layer. In this way, lower conduction resistance RONcan be got in the same breakdown voltage. Thus, the limitation of the silicon could be breakthrough. The electric properties of silicon carbide with super junction schottky diode arestudied and the electric properties when p-Zone and n-Zone in the drift layer are put intodifferent thickness, width and doping concentrations are espectively discussed in thisdissertation. This dissertation also makes use of the two-dimensional simulation software forgetting the diagrammatic electrical properties of the silicon carbide schottky diode. Based onanalying the electrical properties of silicon carbide schottky power switching diodes, theorganization optimization of depth and width are proposed and compare the electric propertiesof optimal structure and the original device.