What does donor doping introduce to a semiconductor?

Donor doping introduces additional mobile electrons to a semiconductor. This process involves adding elements that have more valence electrons than the semiconductor material, typically from group V of the periodic table, such as phosphorus or arsenic when doping silicon, which has four valence electrons.

The dopant atoms donate one extra electron per atom to the conduction band of the semiconductor. Since these extra electrons are not tightly bound to the nucleus, they become mobile and can contribute to electrical conduction, thereby enhancing the semiconductor’s conductivity. This is particularly significant in n-type semiconductors where the conductivity is primarily due to the presence of these additional free electrons.

Other options describe various attributes that do not result from donor doping. For instance, the introduction of additional holes, which refers to the absence of electrons and results in positive charge carriers, instead relates to acceptor doping. Redundant vacancies and deficiencies of electrons do not accurately depict the effect of donor doping, as they imply structural imperfections or a lack of charge carriers rather than the enhancement of electron mobility.