Energy gaps and bowing of interband gaps of lattice matched In/sub 1-x/Ga/sub x/As/sub y/P/sub 1-y//InP

Electroreflectance spectra at low temperature are measured to evaluate the compositional dependence of energy gaps and spin orbit splitting of In/sub 1-x/Ga/sub x/As/sub y/P/sub 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 E/sub 1/ at L changes from a minimum, M/sub 0/, in InP to a saddle point, M/sub 1/, 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.