p-type semiconductors

Now dope silicon with a group III element such as boron (B). Boron has only three outer electrons, so one of its four bonds is an electron short.

Figure to be added

Figure 11.4 — a silicon lattice doped with boron, with the hole the doping produced.

p-type semiconductor

There is a hole where the electron is missing, and holes conduct as positive charges, so this is a positive-type (p-type) extrinsic semiconductor. Holes far outnumber free electrons in it, so holes are the majority carriers and free electrons the minority carriers. Aluminium (Al), gallium (Ga) and indium (In), also in group III, can be used too. Group III elements create holes that can take in electrons, so they are acceptor atoms.

n-type

Doped with a group V element (P, As, Sb): donor atoms.

Extra free electrons carry the current.

p-type

Doped with a group III element (B, Al, Ga, In): acceptor atoms.

Holes are the majority carriers.