Question

A small impurity is added to germanium to get a p-type semiconductor. Identify the impurity?

(a) Bivalent substance

(b) Trivalent substance

(c) Pentavalent substance

(d) Monovalent substance

This question was addressed to me in a national level competition.

I would like to ask this question from Extrinsic Semiconductor topic in section Semiconductor Electronics : Materials, Devices and Simple Circuits of Physics – Class 12

Answer 1

Correct answer is (b) Trivalent substance

The best explanation: A trivalent impurity added to germanium produces a p-type semiconductor. Trivalent impurities such as boron, indium, and gallium are called acceptor impurity. These can be added to germanium in order to obtain a p-type semiconductor.