Abstract
Time-resolved spatial structures of a current density filament in n-GaAs have been investigated under a dc+ac drive voltage Vdc+Vacsin 2π fdt at 4.2 K. With a sinusoidal drive of Vdc=0.95 V, Vac=388 mV and fd=100 kHz, we 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.
