Analysis of a.c. and transient properties of junction transistors through the concept of complex lifetime

A new physical concept of ’ complex lifetime ’ of minority carriers in semiconductors is introduced which helps to visualize the frequency dependence of many properties of semiconductor devices and to evaluate those with very little labour. The calculation of any a.c. property by this method consists of substitution of the ’ complex lifetime ’ (defined for holes as τP*=τP/(1+jωτP), where τP is lifetime) in place of the usual real lifetime in the expression for the corresponding d.c. property. The labour involved in solving the a.c. continuity equation is thus avoided, and many results which otherwise involve a lot of algebra are easily derived. With the addition of this concept, the stored charge method can be readily extended for the quantitative evaluation of a.c. properties. A generalization of this concept is also introduced which simplifies the calculation of the transient performance of transistors. © 1970 Taylor and Francis Group, LLC.