How does boron doping create a p-type silicon semiconductor?

Boron doping creates a p-type semiconductor by introducing an impurity with fewer valence electrons than the host silicon atoms.

In a pure silicon crystal, each atom shares four electrons with its neighbors to form stable covalent bonds. Boron, however, is a trivalent atom, meaning it has only three electrons available for bonding. When a boron atom is substituted for a silicon atom in the crystal lattice, it lacks the fourth electron necessary to complete the four covalent bonds with its neighboring silicon atoms.

This deficiency creates an electron vacancy, known as a hole, in the valence band. Because this hole acts as a mobile, positively charged site that can accept an electron from a neighboring bond, the boron atom functions as an acceptor. The presence of these holes allows for electrical conduction through the migration of the positive charge carriers, characterizing the material as p-type (where p stands for positive).12