Title :
Doped contacts for high-longevity optically activated, high-gain GaAs photoconductive semiconductor switches
Author :
Mar, Alan ; Loubriel, Guillermo M. ; Zutavern, Fred J. ; O´Malley, Martin W. ; Helgeson, Wesley D. ; Brown, Darwin J. ; Hjalmarson, Harold P. ; Baca, Albert G. ; Thornton, R.L. ; Donaldson, R.D.
Author_Institution :
Sandia Nat. Labs., Albuquerque, NM, USA
fDate :
10/1/2000 12:00:00 AM
Abstract :
The longevity of high-gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 100 million pulses. This was achieved by improving the ohmic contacts through the incorporation of a doped layer that is very effective in the suppression of filament formation, alleviating current crowding. Damage-free operation is now possible at much higher current levels than before. The inherent damage-free current capacity of the bulk GaAs depends on the thickness of the doped layers and is at least 100 A for a dopant diffusion depth of 4 μm. This current could be increased by employing multiple switches connected in parallel. The contact metal has a different damage mechanism, and the threshold for damage (~40-80 A) is not further improved beyond a dopant diffusion depth of about 2 μm. In a diffusion-doped contact switch, the switching performance is not degraded at the onset of contact metal erosion, unlike a switch with conventional contacts. For fireset applications operating at 1-kV/1-kA levels and higher, doped contacts have not yet resulted in improved longevity. We employ multifilament operation and InPb solder/Au ribbon wirebonding to demonstrate >100-shot lifetime at 1-kV/1-kA
Keywords :
gallium arsenide; ohmic contacts; photoconducting switches; 40 to 80 A; GaAs; contact metal erosion; damage-free current capacity; damage-free operation; diffusion-doped contact switch; dopant diffusion depth; doped contacts; doped layers; filament formation; high-gain GaAs photoconductive semiconductor switches; multifilament operation; multiple switches; ohmic contacts; switching performance; Contact resistance; Degradation; Furnaces; Gallium arsenide; Ohmic contacts; Optical switches; Photoconducting devices; Proximity effect; Silicon compounds; Zinc;
Journal_Title :
Plasma Science, IEEE Transactions on