109 research outputs found
Theory of superfast fronts of impact ionization in semiconductor structures
We present an analytical theory for impact ionization fronts in reversely
biased p^{+}-n-n^{+} structures. The front propagates into a depleted n base
with a velocity that exceeds the saturated drift velocity. The front passage
generates a dense electron-hole plasma and in this way switches the structure
from low to high conductivity. For a planar front we determine the
concentration of the generated plasma, the maximum electric field, the front
width and the voltage over the n base as functions of front velocity and doping
of the n base. Theory takes into account that drift velocities and impact
ionization coefficients differ between electrons and holes, and it makes
quantitative predictions for any semiconductor material possible.Comment: 18 pagers, 10 figure
Dynamic avalanche breakdown of a p-n junction: deterministic triggering of a plane streamer front
We discuss the dynamic impact ionization breakdown of high voltage p-n
junction which occurs when the electric field is increased above the threshold
of avalanche impact ionization on a time scale smaller than the inverse
thermogeneration rate. The avalanche-to-streamer transition characterized by
generation of dense electron-hole plasma capable to screen the applied external
electric field occurs in such regimes. We argue that the experimentally
observed deterministic triggering of the plane streamer front at the electric
field strength above the threshold of avalanche impact ionization but yet below
the threshold of band-to-band tunneling is generally caused by field-enhanced
ionization of deep-level centers. We suggest that the process-induced sulfur
centers and native defects such as EL2, HB2, HB5 centers initiate the front in
Si and GaAs structures, respectively. In deep-level free structures the plane
streamer front is triggered by Zener band-to-band tunneling.Comment: 4 pages, 2 figure
Generation of High-Voltage Pulses by Sharp-Recovery SiC Drift Diodes (n-Base versus p-Base Diodes)
- …