Effect of temperature on avalanche region width and DC to RF conversion efficiency of the p+nn−n+ 4H–SiC impact avalanche transit time diodes

The effect of temperature on avalanche region width and DC to RF conversion efficiency of the p+nn−n+ impact ionization avalanche transit time diodes based on 4H–SiC material for 140 GHz design frequency has been investigated by means of the MEDICI simulation platform. It is shown that the avalanche region width of the IMPATT diodes working at the same operating current densities first decreases and then increases with the increasing temperature. The DC to RF conversion efficiency of the IMPATT diodes first increases and then decreases with the increasing temperature. The increase in ionization rate of impurities with increasing temperature and the decrease in the carrier impact ionization rate with increasing temperature are responsible for the results. In addition, the expansion of avalanche region and the degradation of DC to RF conversion efficiency at lower temperature are more pronounced in lower p+ region doping concentration diode than that in higher p+ region doping concentration.