MICROSCOPIC THEORY OF SUPERCONDUCTING CONTACTS WITH INSULATING BARRIERS

We analyze contacts like SININ and SINIS with dielectric barriers I. On the basis of a microscopic theory, we obtain the matching conditions at the SIN boundary for the distribution functions. The I(V) characteristics are found for the SININ contacts with a length exceeding the correlation length-xi. It is shown that in contacts with a high transmittance of the SIN interface an excess current I(exc) > 0 appears at high voltages. In contacts with a low transmittance a deficit current I(def) < 0 at high V and a peak in the conductance at low V exist. Both I(exc) and I(def) diminish with increasing the contact length d. The zero-bias anomaly is suppressed by temperature and a weak magnetic field.