I dont wish to go down th eroad of semiconductor theory, holes electron mobility et-al.........suffice to say that, silicon transistors do posses some superior qualities compared with their germanium counter parts....again its a case of selecting the appropriate device for the given design....
Kinjalp...sorry I disagree with the statement,
PNP transistors cannot handle very high powers. They are used for small signal or medium power applications.
While, NPN transistor can handle very high currents and thus are used in majority of high power amps apart from small signal and medium power applications.
Take for instance the device MJ3055, a high power silicon NPN power transistor.......it has a PNP counterpart the MJ2955.......
at the other end of the scale in terms of power ratings, the BC series, 547/557 are npn/pnp devices......