In doping an intrinsic semiconductor to produce a p-type semiconductor,

Analyze the question: It asks what is done when doping an intrinsic semiconductor to make a p-type semiconductor.

Concept:

• An intrinsic semiconductor is pure (e.g., silicon or germanium, Group IV) with equal numbers of electrons and holes.
• Doping means adding a small amount of impurity atoms to increase conductivity.
• p-type: a trivalent impurity (Group III, e.g., boron, aluminium, gallium, indium) is added. Each impurity atom has only 3 valence electrons, so it leaves a missing electron (a hole) in a covalent bond. It readily accepts an electron, so it is called an acceptor. Holes become the majority carriers (p = positive).
• n-type: a pentavalent impurity (Group V, e.g., phosphorus, arsenic, antimony) is added. It has 5 valence electrons, so it donates a free electron. It is called a donor, and electrons become the majority carriers.

Solution:

• A. Heating only produces more electron-hole pairs (thermal excitation). It is not doping and does not make the material p-type.
• B. A donor element produces an n-type semiconductor, so this is wrong.
• C. An acceptor element (trivalent) creates holes, giving a p-type semiconductor. This is correct.
• D. Connecting to a battery is biasing, not doping.

Answer: C. an acceptor element is added

Tip: Remember "P-type = Positive holes = Acceptor (Group III, 3 valence electrons)", and "N-type = Negative electrons = Donor (Group V)". Pair them as Acceptor → p, Donor → n.