Why does the conductivity of silicon increase upon doping with phosphorus ?

Account for the following : (i) Schottky defects lower the density of related solids. (ii) Conductivity of silicon increases on doping it with phosphorus.

Account for the following: (i) schottky defects lower the density of related solids. (ii) Conductivity off silicon increases on doping it with phosphorus.

Account for the following : (i) Schottky defects lower the density of related solids. (ii) Conductivity of silicon increases on doping it with phosphorus.

Account for the following : (i) Schottky defects lower the density of related solids. (ii) Conductivity of silicon increases on doping it with phosphorus.

Account for the following: Conductivity of silicon increases on doping it with phosphorus.

Expalin why does conductivity of germainum crystals increase on doping with galium ?