Question

Silicon by doping with phosphorous forms n type semiconductor? Why

Answer 1

bcoz phosphorus is pentavalent atom.
after forming 4 bonds with si it's 1 electron remains free which contributes to the conductivity of semiconductor ...

Answer 2

Hey !!

Phosphorous is an electron rich element of group 15. On doping with element of group 14, silicon, an n-type semiconductor will form because here the conductivity is due to the presence of extra electron.

GOOD LUCK !!