Silicon diodes are preferred to germanium diodes for high

Silicon diodes are preferred to germanium diodes for high temperature operation because:

1. doping of silicon is a simple processes
2. rate of increase of reverse saturation current with temperature is more in the case of silicon
3. the reverse saturation current of silicon diodes is smaller than that of germanium
4. silicon diodes can be used to rectify even very small voltage

Silicon diodes are preferred to germanium diodes because the reverse saturation current of silicon diodes is smaller than that of germanium.