Self-consistent, 2D simulations of filament propagation in photoconducting switches

摘要

The authors present simulations of time-dependent filament propagation in laser-triggered GaAs photoswitches. Unlike previous modeling, the calculations are self-consistent in 2-D axisymmetric (r-z) geometry. Realistic electron and hole mobilities as well as field dependent impact ionization are included. The authors report filament propagation with speeds U(sub f) (approx) 10(sup 8)--10(sup 9) cm/s, much larger than the saturated carrier drift velocity, u(sup sat) (approx) 10(sup 7) cm/s. The self-consistently determined filament radius and carrier number density are typically R(sub f) (approx) 20--60 (mu)m and n(sub f) (approx) 10(sup 17)--10(sup 18) cm(sup (minus)3) respectively. Results are presented for filament propagation in systems with both uniform and nonuniform profiles of background carrier density and electric field.