In this mode, electrons are injected from [n.sup.++] emitter region
into p base region, and holes are injected from p base region into [n.sup.++] emitter region
However, it does not show much effect in the case of recombination currents due to the contacts especially in the emitter region
. This happens because the emitter in IBC structure is always wider than the BSF region.
The combination of (1), (2) and (5) allows obtaining the following expression describing the distribution of holes in the emitter region
However, since heavy doping can also bring about an increase in recombination loss in the emitter region, [V.sub.OC] was saturated at [N.sub.B] >5x [10.sup.18] atoms/[cm.sup.3].
In order to confirm the recombination loss in the emitter region for the high doping concentration of boron, internal quantum efficiency (IQE) of the cell was calculated along the [N.sub.B] as shown in Figure 3.Inthe short wavelength range, IQE rapidly decreased at [N.sub.B] >1 x [10.sup.19] atoms/[cm.sup.3], while there was no significant difference in the long wavelength range.
The results are shown in Figure 6 for a multirow power cell and for a close view of the emitter region
. The measurements were obtained under full RF drive and a base temperature of +85[degrees] C.
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 0.5 [[micro]meter] (possible because of the process' self-alignment features) ensure a high [f.sub.max] and low base resistivity.
The steep doping profiles of the base and emitter regions
create the narrow base widths required for a high cutoff frequency while submicron emitter widths ensure a high [f.sub.max] and low base resistivity.