The combination of (1), (2) and (5) allows obtaining the following expression describing the distribution of holes in the emitter region
The results are shown in Figure 6 for a multirow power cell and for a close view of the emitter region
The reason for this is the very low impedance metallization that forms the source terminal covering both the Base and Emitter regions
, thereby maintaining the parasitic NPN in its off condition.
Steep doping profiles of the base and emitter regions
create these very narrow base widths required for a high cutoff frequency, while submicron emitter widths of typically 0.