4. Elements of comparison for power semiconductors

4.1 Performance compromises

• The conclusion to be drawn from the above is that, for each type of component, voltage withstand, current rating and dynamic performance are intrinsically linked, mainly via the thickness and resistivity characteristics of the region constituting the "base" of the device. Thus, the increase in voltage withstand, requiring greater thickness and resistivity from the base, is generally accompanied by a reduction in current capacity per unit crystal area, which is more severe in unipolar components than in bipolar ones, where the resistance of this region can be modulated by the injected carriers. Correlatively, the charge storage involved in conductivity modulation means that the dynamic performance of bipolar devices degrades much more...