Variation of high frequency negative resistance of silicon N+pp+ and GaAs p+nn+ IMPATT diodes with enhancement of reverse saturation current

Computer studies are carried out on the effect of electron and hole reverse saturation currents on i) the negative resistance profiles, ii) the admittance characteristics, and iii) device quality factor (Q) of silicon n+pp+ and GaAs p+nn+ IMPATTs operating in the Ku-band frequencies. The results show that the diode negative resistance decreases first appreciably and then increases again in the case of GaAs p+nn+ diode with the increase of electron reverse saturation current i.e., with the decrease in electron multiplication factor. In the case of silicon n+pp+ diode, the negative resistance increases first and then starts decreasing with the lowering of the hole multiplication factor. It is further observed that for both, Si and GaAs diodes the frequency of operation shifts upwards and the device Q factor increases gradually while the device negative conductance decreases with increasing reverse saturation current.