Advanced Placement (AP) Chemistry Practice Exam

When p-doping occurs in a semiconductor, it involves the introduction of acceptor impurities, which are elements that have fewer valence electrons than the semiconductor material, typically silicon. For silicon, which has four valence electrons, a common dopant is boron, which has three valence electrons.

When boron is introduced into the silicon lattice, it replaces a silicon atom. However, because boron has one fewer valence electron, it does not provide enough electrons to form the normal covalent bonds with the surrounding silicon atoms. This results in an absence of an electron, creating a "hole" in the lattice. The hole is considered to be positively charged because it represents a lack of a negatively charged electron.

These holes can move through the semiconductor material, effectively allowing for electrical conduction. As more acceptor atoms are introduced through p-doping, more holes are created, enhancing the p-type conductivity of the semiconductor.

Thus, the creation of a hole, which acts as a carrier of positive charge, is the key aspect of p-doping in a semiconductor.