Time-resolved spatial structures of periodically-driven current filament in n-GaAs

Time-resolved spatial structures of a current density filament in n-GaAs have been investigated under a de + ac drive voltage V-dc + V-ac sin 2 pi f(d)t at 4.2 K. With a sinusoidal drive of V-dc = 0.95 V. V-ac = 388 mV and f(d) = 100 kHz, me observe an S-shaped I-V curve caused by the impact ionization avalanche of neutral shallow donors and subsequent formation of a current density filament. Evolution of the current-density filament was studied by the time-resolved measurements of the photoluminescence quench-patterns. A new finding is the Turing bifurcation observed at around the breakdown voltage.