Theoretical transient currents from two-component unipolar space-charge swarms in fields in media

Abstract

Using an arbitrary initial unipolar space-charge distribution consisting of two species of charge carriers of different but constant mobilities in a medium, relations for the electric fields and charge-carrier densities are derived as functions of positions and time. The highly nonlinear, one-dimensional equations, which are derived for swarms of charge carriers between parallel plane electrodes with a fixed potential difference, include the effects of the space-charge fields. A general method is outlined which, in principle, can be used to generate a second order differential equation whose solution predicts the time-dependent current caused by the drifting space-charge swarm. The general equations are applied to the special case where the initial space-charge distributions are uniform in a solid or fluid medium. Although the resulting differential equation is complicated, the equation is in a form such that its solutions could be computer generated.