Energy gaps and bowing of interband gaps of lattice matched In1-xGaxAsyP1-y/InP

Electroreflectance spectra at low temperature are measured to evaluate the compositional dependence of energy gaps and spin orbit splitting of In_1-xGa_xAs_yP_1-y alloys at different points in the Brillouin zone. The Kramers-Kronig transformation of reflectance spectra provides the Seraphin coefficients for a quantitative lineshape analysis which improves further the accuracy of the band gaps derived. The band gap E₁ at L changes from a minimum, M₀, in InP to a saddle point, M₁ , in the alloys. Collisional broadening varies with composition and increases for all compositions strongly with energy. The bowing parameter vary strongly for different gaps in contrast to commonly used models