Zone-centre bands of a zinc-blende III-V semiconductor

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.