We have measured phase modulation in the first chemical beam epitaxy grown InGaAsP/InP barrier, reservoir, and quantum well electron transfer structures. We obtain a negative refractive index change, DELTAn, similar to that found in the InGaAs/InAlAs system. Using new designs to reduce the leakage current in this material system, we obtain a leakage current <1 A/CM2. Our results show an unexpected negative DELTAn for both positive and negative bias, which we explain using calculations of the wave function.