AbstractThe theory of point defect ionization in semiconductors by the streamer discharge electric field is developed. It is shown that due to high streamer velocity and sharp spatial inhomogeneity of the electric field defect ionization is a fast quantum process with a large energy uncertainty of particles involved and, hence, it does not occur by tunneling. Localized wavefunctions are described by the quantum defect method. The ionization probability is calculated and its straightforward dependence on the velocity and the form of the streamer field and the defect parameters is determined. As in the case of interband transitions considered in the first work the ionization probability is an increasing function of the streamer velocity and the field steepness.