Acceptor (semiconductors)

When silicon (Si), having four valence electrons, is doped with elements from group III of the periodic table, such as boron (B) and aluminium (Al), both having three valence electrons, a p-type semiconductor is formed.

Other trivalent dopants include indium (In) and gallium (Ga).

[1] When substituting for a silicon atom in the crystal lattice, the three valence electrons of boron form covalent bonds with three of the Si neighbours but the bond with the fourth remains unsatisfied.

This chain-like process results in the hole moving around the crystal as a charge carrier.

This process can sustain in an electric current useful in electronic circuits.