Why is silicon wafers preferred over Germanium wafers?
Germanium was in the first transistors. These transistors were meant to replace the vaccum tubes found in World War Two era Radar. The military wanted smaller, lighter and more powerful radar to bomb Germany.
But the ware ended and the military's, spare-no-cost, attitude became more frugal.
With the research open to the public, commercial entities discovered that Silicon worked very well in consumer items such as portable transistor radios. Thus Silicon, which is more abundant and less expensive than Germanium became the standard material and is still being used today and for the foreseable future.