Measurement of the velocity of current filaments in optically triggered, high gain GaAs switches

Abstract

Pictures are presented of the time evolution of current filaments during 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 switch 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±1×109 cm/s, 100 times larger than the peak drift velocity of carriers in GaAs. This observation supports switching models that rely on carrier generation at the tip of the filament.

“S-shaped” negative differential conductivity of high gain GaAs photoconductive switches

“…High gain GaAs photoconductive semiconductor switches (PCSS) exhibit unique properties associated with lock-on which is characterized by filamentary currents [1][2][3]. "S-shaped" current-voltage (I-V) characteristics of the device are therefore expected for the current filament fonnation [4,5].…”

Surface-related breakdown in silicon: Imaging of current filaments in long p+-n−-n+ structures

“…This minimum value is three times the 1ϫ10 7 cm/s saturation drift velocity for electrons in silicon, 18 but below typical streamer velocities observed in gases, 19 and well below velocity estimates for streamers in gallium arsenide. 20,21 This work was supported by the Office of Naval Research under Grant No. N00014-92-J-4028.…”

Current Filament Semiconductor Lasers (CFSL)

“…a spectra string, e.g. : 'BBcd [3,5,9]' (if omitted, empty, or zero, a gain of 1 is used) temp -the filament temperature to remove the black blody shape (only used when gain is a text matrix of black body spectra) (if omitted, empty, or zero, a zero slope is used) iedge -number of pixels to omit from each edge of the spectra (bkg and gain of zero will be returned for these pixels) cosmic -remove cosmic rays from data files with double pass filter (see cosmicut) If a0 cosmic rays will be removed with r=cosmic. If =0 no cosmic rays will be removed.…”