The growth of GaAs quantum well modulators on Si for photonic switching applications is reported. Comparison of modulator’s quantum confined Stark effect atop different miscut Si surfaces demonstrate the need for a highly ordered array of bilayer steps as an initial Si surface condition for heteroepitaxy. Proton implantation into the SiO2/Si system via an electron cyclotron resonance plasma to lower the Si oxide desorption temperature, while perserving step ordering of the surface, is explored.