We report on optical and electrical properties of modulation doped InxGa1−xAs/InP single quantum wells in the composition range 0.56≤x≤0.79. Cyclotron resonance, contactless Shubnikov–de Haas and magnetophotoluminescence experiments are used to obtain two dimensional carrier densities, effective masses of electrons and holes and scattering times. We present data which give evidence for zero magnetic field spin splitting. The dispersion relation for electrons and holes is presented. ©1996 American Institute of Physics.