Question

What are the charge carriers in p-type of semiconductors?

Hint:

Trivalent (acceptor) doping creates vacancies; recall which positive carrier dominates in p-type.

Answer 1

Step 1: How a p-type semiconductor is made.
A pure (intrinsic) semiconductor such as silicon or germanium is doped with a small amount of a trivalent impurity (an acceptor atom having 3 valence electrons, for example boron, aluminium or indium).

Step 2: What this creates.
Each trivalent atom forms only three covalent bonds with the neighbouring silicon atoms; the fourth bond is left incomplete, creating a vacancy called a hole. These holes are far more numerous than the electrons.

Step 3: The charge carriers.
Therefore, in a p-type semiconductor the majority charge carriers are holes (positive), while electrons are the minority carriers.

\[\boxed{\text{Majority carriers = holes (positive); minority = electrons}}\]