Why sillicon diode is used in most of application?

Answer 1

silicon is the most commonly used semiconductor. As it is abundant and inexpensive. However, it also has the advantage of a great oxide layer (silicon dioxide) which serves as as dielectric in many applications, and as a result it is relatively easy to make devices out of Si. It's this oxide layer that makes silicon more common than germanium, which does not readily form an oxide layer because Ge has less affinity with oxygen when compared to Si, even though the there are many charge carriers in Ge as compared to Si its the ability to form the oxide layer which makes Si more preferable than Ge