A GaAs avalanche diode analysis and an approximate indirect measurement of hole saturation velocity

GaAs avalanche diodes are observed to operate at frequencies considerably lower than those of Si or Ge diodes with similar doping profiles and dc characteristics. This observed behavior and the analysis shown in this paper enable us to evaluate an approximate hole saturation velocity in GaAs. Small signal impedances and Q's of GaAs avalanche diodes with breakdown voltages of 17, 36, and 58 are calculated based on the approximated hole saturation velocity of
2 \times 10^{6}
cm/s. The model assumes an abrupt p
⁺
-n junction, e.g., zinc diffusion on n-type material, and a realistic electric field in the space-charge region.