Gm. Loubriel et al., MEASUREMENT OF THE VELOCITY OF CURRENT FILAMENTS IN OPTICALLY TRIGGERED HIGH-GAIN GAAS SWITCHES, Applied physics letters, 64(24), 1994, pp. 3323-3323
Pictures are presented of the time evolution of current filaments duri
ng optically triggered, high gain switching in GaAs. Two filaments are
triggered with two laser diode arrays and the time delay between them
is varied. When the filament that is triggered first crosses the swit
ch the voltage drops and the other filament ceases to grow. By varying
the delay between the lasers, the tip velocity is measured to be 2 +/
- 1 x 10(9) cm/s, 100 times larger than the peak drift velocity of car
riers in GaAs. This observation supports switching models that rely on
carrier generation at the tip of the filament.