III-V semiconductor

A compound semiconductor built from group-III and group-V elements, such as gallium arsenide. Many common members have a zinc blende structure, while other materials or growth conditions give a wurtzite structure. The chemical family alone does not fix a direct rather than indirect gap or a particular band ordering.

A compound of aluminium and phosphorus, with two chemical atoms per primitive unit cell in its usual zinc blende structure. Its two inequivalent atomic basis sites give six phonon branches, three acoustic and three optical.

A common unstrained cubic III-V band ordering consists of an s-like ${\Gamma }_{6c}$ conduction doublet, a p-like ${\Gamma }_{8v}$ quartet and a lower spin-orbit split-off ${\Gamma }_{7v}$ doublet. In the cubic limit the quartet gives heavy-hole and light-hole bands that meet at the Gamma point; different curvatures and direction-dependent mixing distinguish them away from it. The split-off valence band is separated by ${\Delta }_{\mathrm{so}}$. This common ordering is a model to check against the actual material, not a consequence of chemical stoichiometry alone.