1. Semiconductor Switch Simulations Texas Tech U. & Sandia National Labs
Goals
Simulations: Breakdown & “lock-on” in photoconductive semiconductor switches (PCSS’s)
Understand the behavior of GaAs, Si, & InP PCSS’s at 4 to 30 kV/cm fields.
Approach
Collective impact ionization theory: Effect of carrier-carrier scattering on impact ionization.
Simulations: Ensemble Monte Carlo & Maxwellian distribution
Results: Generalized Breakdown
Breakdown & “lock-on”: Two aspects of the same phenomenon
Steady state electric field (F) & carrier density dependence (n) of breakdown
Personnel: Ken Kambour, PhD student/Sandia visitor; H.P. Hjalmarson (Sandia), C.W. Myles (TTU)
Fig. 1. Photoconductive switch (PCSS) with optical illumination and current filaments
Fig. 2. Generalized Breakdown (Model Material): n vs. F: Minimum F on curve = Breakdown field without (red) & with (blue) carrier-carrier (CC) scattering.  CC-scattering lowers the breakdown field. “Lock-on” = Breakdown with CC scattering.