Optimum design for high-power and high-efficiency GaAs Hi-Lo IMPATT diodes

Optimum structure parameters of GaAs hi-lo IMPATT diodes to give a high-efficiency and a high-output power are experimentally determined in the frequency range from 7 to 18 GHz. The highest efficiency is obtained at any frequency when a diode has a punch-through factor of about 0.6 and is depleted with an electric field strength of 10 kV/cm at the end of the lo region under operation. The optimum lo-region carrier concentration to achieve the highest efficiency and the upper limit of a junction area to obtain a high-output power without decreasing efficiency are found to be simply related to frequency by the following equations:
(N_{L})_{\opt} = (4 \times 10^{14}) \cdot (f/7)^{3}
cm
^-3
and
(S_{j})_{\max} = (20 \times 10^{-4}) \cdot (f/10)^{-1.9})
cm
²
), respectively, where
f
is in gigahertz.