High‐voltage silicon photoconductive switches require pulse bias in order to prevent thermal runaway. The behavior of these devices during pulse bias cannot be modeled by standard steady‐state current equations (Ohm’s law). This paper shows that the observed nonlinear behavior is due to plasma injection, describes an analysis of this transient current flow during pulse bias, and shows it to be in good agreement with our experimental results. This paper further verifies the charge injection by showing that the leakage current can be reduced by thin trap layers directly underneath the metal contacts.