We have investigated the electroabsorption due to the Franz–Keldysh effect in GaInP/AlGaInPp-i-ndouble heterostructures grown by metalorganic vapor phase epitaxy. The simultaneous evaluation of transmission and photocurrent measurements allowed an accurate determination of the field dependent absorption coefficient of ordered and disordered GaInP alloys. For ordered and disordered material, similar changes of the absorption coefficient as high as 4000 cm−1have been observed for field changes of&Dgr;E=250kV/cm. Thermally disordered samples, however, showed a degradation of the electrical and optical properties. ©1997 American Institute of Physics.