Reverse transient characteristics of a P-N junction diode due to minority carrier storage

Abstract

Analysis of the transient switching characteristics of a p-n junction diode is considered a boundary value problem; solution of this problem yields mathematical equations applicable to the design of high-speed computer components. This analytical technique is used to establish the transient current of a semiconductor diode when an external biasing potential is rapidly switched from the forward to the reverse direction. Using a one-dimensional model of finite geometry, minority-carrier storage is assumed within a region of arbitrary lifetime, bounded on one side by the junction and on the other side by an ohmic contact of arbitrary recombination velocity. Further, this region of carrier storage is assumed to contain a drift field of constant magnitude as would result from an exponential type of conductivity grading. Mathematical equations are presented which characterize this transient situation from its initiation until the junction current has decayed to some arbitrary magnitude. Applications of this analysis are illustrated in graphical form throughout a range of parameters characterizing practical semiconductor devices.