Asymptotes for boundary determined current density of PIN diodes

A general boundary determined equation is used to obtain the physical asymptotes for the current density of PIN diodes. Application of this equation indicates that lower level injection regions are degenerate versions of the higher level regions. Other methods depend upon precise knowledge of the carrier density profile whereas the present approach only requires a notional indication of the ratio of minimum to boundary carrier densities. This ratio is an important determining factor for the gradient of boundary carrier density which exerts a strong influence upon boundary current density. A theoretical basis is laid which explains the link between the various ranges of injection level. This asymptotic approach could provide an effective method in applying charge control models for transient analysis over wide ranges of current.