Impact ionization and neutral base recombination in SiGe HBTs

Both neutral base recombination and impact ionization tend to reduce the base current with increasing V/sub CB/. Contrary to other publications, no experimental evidence for neutral base recombination is found in our SiGe HBTs. In particular, temperature measurements of the CB diode of the SiGe HBTs did not show any difference compared to the Si control transistors.