Extrinsic Semiconductor - p-type semiconductor

• The semiconductor in which a silicon or germanium crystal is doped with a trivalent impurity (acceptor), making holes the majority charge carriers, is called a p-type semiconductor.
• On doping an intrinsic semiconductor with trivalent impurity like Indium (In) or Gallium (Ga), the semiconductor becomes deficient in electrons, i.e., the number of holes becomes more than the number of electrons. Such a semiconductor is called p-type.

The trivalent impurity atom added during doping in a p-type semiconductor is known as an acceptor.

• A p-type semiconductor is formed by doping with a trivalent impurity (e.g., Indium, Gallium, Boron).
• The trivalent impurity has 3 outer electrons, creating a hole in the crystal lattice where no electron is present.
• Due to a lack of electrons, the Fermi level shifts closer to the valence band.
• Holes are majority carriers; electrons are minority carriers — nh≫nenh​≫ne.
• The acceptor energy level lies approximately 0.01 to 0.05 eV above the valence band.