How can tiny amounts of boron change silicon’s electrical conductivity?

In materials science, the process of intentionally adding impurities to a semiconductor to modify its electrical conductivity is known as doping. While pure (intrinsic) silicon is a poor conductor at room temperature, introducing tiny amounts of specific elements can significantly enhance its ability to conduct electricity.12

When boron—a trivalent atom with only three outer electrons—is substituted for a silicon atom in the crystal lattice, it lacks the fourth electron necessary to complete the covalent bonds with its four neighboring silicon atoms. To form these four bonds, the boron atom accepts an electron from the surrounding structure, which creates a positively charged vacancy known as a hole in the valence band.123

Because boron acts as an "acceptor" of electrons, it creates a p-type semiconductor. Under the influence of an electric field, these holes can migrate through the crystal lattice, effectively acting as positive charge carriers that increase the material's overall electrical conductivity.132