Nonlinear electrical conductivity of a point-contact junction containing a planar defect

The influence of the interaction between electrons and phonons localized near a planar defect on the nonlinear electrical conductivity of small-size junctions is studied theoretically. The normalized second derivative of the current-voltage characteristic exhibits singularities due to inelastic relaxation of carriers by interaction with such phonon states. In strong magnetic fields and also in the case of strong elastic scattering of electrons by a defect, the surface contribution predominates over the contribution of the bulk electron-phonon interaction to the point-contact spectrum