Direct-gap reduction and valence-band splitting of ordered indirect-gap AlInP2 studied by polarized piezoreflectance

The order-dependent direct-gap reduction and valence-band splitting in spon taneously ordered indirect-gap AlInP2 are determined by polarized piezorefl ectance spectroscopy at room temperature. The experimentally deduced values of the ratio of band-gap reduction to crystal field splitting for the perf ectly ordered alloys, zeta = -DeltaE(g)((1))/Delta ((1))(CF) = 1.15. and th e ra-xi tio of band-gap reduction to the ordering change of spin-orbit spli tting between the perfectly ordered and random alloys, xi = -DeltaE(g)((1)) [Delta ((1))(SO) - Delta ((0))(SO)] = 8.24, are in good agreement with the recent theoretically calculated value of 1.13 and 13.5, respectively, by [S . H. Wei and A. Zunger. Phys. Rev. B 57, (1998) 8983] but are much larger t han those of the previous report by [M. Schubert et al.: Phys. Rev. B 54 (1 996) 17616] using dark-field spectroscopy.