Section 1–4

• An n-type semiconductive material is created by adding impurity atoms that have five valence electrons. These impurities are pentavalent atoms. A p-type semiconductor is created by adding impurity atoms with only three valence electrons. These impurities are trivalent atoms;
• The process of adding pentavalent or trivalent impurities to a semiconductor is called  doping;
• The majority carriers in an n-type semiconductor are free electrons acquired by the doping process, and the minority carriers are holes produced by thermally generated electron-hole pairs. The majority carriers in a p-type semiconductor are holes acquired by the doping process, and the minority carriers are free electrons produced by thermally generated electron-hole pairs;