Polarized band-edge photoluminescence and ordering in ${\mathrm{Ga}}_{0.52}$${\mathrm{In}}_{0.48}$P

We present the first experimental evidence for the spontaneous breaking of cubic symmetry in the band structure of films of ${\mathrm{Ga}}_{0.52}$${\mathrm{In}}_{0.48}$P grown by organometallic vapor-phase epitaxy on (100) GaAs substrates. We show how this effect is related to the spontaneous ordering of the alloy, and its correlation with the anomalous lowering of the band gap observed in these films.