On the current-voltage characteristics of n+-p-p+diodes

The
J-V
characteristics of n
⁺
-p-p
⁺
diodes are analyzed based on the assumption of negligible recombination in the lowly-doped base. The analysis represents a generalization of the approach used by Mertens et al. [1] for high-injection conditions and is valid for all injection levels. Two coupled nonlinear equations from which the
J-V
characteristics can be calculated are derived. It is shown that under high-injection conditions the equations reduce to those by Mertens et al. For low-injection conditions the electron current density J
n
and hole current density J
p
are decoupled and single equations are obtained for J
n
and J
p
, respectively. For the case where the back side contact approaches an ohmic contact, the classical equation for a short-base diode results. The analysis is justified by very close correspondence with exact numerical calculations using the Finite Element Device Analysis Program (FIELDAY).