Hole-doping of a semiconductor by a strong acid. First, the H+ cations (red) and their associated anions
(green) dissociate in water. The cations attach themselves to the material, attracting electrons (yellow) from
inside the bulk (grey). The electrons then form dipoles with the H+ ions, leaving holes behind in the material
and lowering the Fermi level. The holes can then move through the material, carrying positive charge.