Answer
Silicon is abundant in nature as SiO2(sand).
Getting the Si from SiO2 is comparatively easier than other semiconductors like Ge.
And Silicon is a better conductor at room temperature.
valence electron in germanium are in fourth shell whereas on silicon valence electron is in third shell.
germanium valence electron are at higher energy level than silicon .hence germanium valence electron will need smaller amount of energy to escape form the atom due to this germanium more number of electron pair than silicon . hence leakage current is more.
this property makes germanium more unstable at high temperature.
