Radiative recombination of the excitonic states in semiconductor superlattices with an applied electric field is studied theoretically. It is shown that when the electron‐hole Coulomb interaction energy exceeds the miniband width, a coherent excitonic state is created whose oscillator strength surpasses the oscillator strength of a single quantum well by orders of magnitude. It is also demonstrated that a small external field can split the coherent state into isolated well states and thus severely deplete the oscillator strength of the exciton. This opens the possibility of modulating and switching of superradiance in semiconductor devices. ©1995 American Institute of Physics.