Question

The impurity atoms with which pure silicon may be doped to make it a p-type semiconductor are those of
(a) phosphorus
(b) boron
(c) antimony
(d) aluminium.

Answer 1

(b) boron
(d) aluminium

A p-type semiconductor is formed by doping an intrinsic semiconductor with a trivalent atom (atom having valency 3). As phosphorous and boron have three valence electrons, they can be doped with silicon to make a p-type semiconductor.