Question

What is the function of a dopant?

1) To ionize gas atoms
2) To improve the mechanical strength of a substance
3) To alter the electrical or optical characteristics of a substance
4) To produce short bursts of intense light

Answer 1

3), A dopant is used to alter the electrical or optical properties of a substance by introducing changes in its conductivity. This is primarily used in the creation of semiconductors, leading to either an n-type or p-type semiconductor based on the type of impurity added.

Step-by-step explanation:

The function of a dopant is to alter the electrical or optical characteristics of a substance, particularly in the context of semiconductors. When a dopant is introduced into a semiconductor, such as silicon, it creates dopant-induced defects that play a crucial role in determining the material's conductivity. Doping can transform an intrinsic semiconductor into an extrinsic one, called an n-type semiconductor when donor impurities with more valence electrons than the host are added, or p-type semiconductor when acceptor impurities with fewer valence electrons are used. For instance, adding phosphorus (which has five valence electrons) to silicon (which has four valence electrons) creates a n-type semiconductor because the additional electron from each phosphorus atom contributes to electrical conductivity. Conversely, incorporating boron (with three valence electrons) creates a p-type semiconductor because holes (positive charge carriers) are created when boron atoms replace silicon in the lattice.