  Extended BTK-type theoretical methods were used for the calculation of
conductance spectra of NS and NIS junctions, where S is either a d-wave or a
d+is-wave superconductor, and N is a normal metal. We found that the length
scale over which the bulk d-wave order parameter varies spatially near the
interface (the "decay length") has a significant effect on the main features of
the conductance spectra. A relatively large decay length of the order of
10-20$\xi_{0}$ together with a small $is$-wave component, can explain many
peculiarities observed in the experimental conductance spectra of various
junctions. We attribute the long decay length to either a reversed proximity
effect in the high transparency junctions, or to the presence of a low $T_c\leq
10$K s-wave component with a much longer $\xi_{0s}\approx 10\xi_{0d}$ near the
interface.

Superconductivity;Strongly Correlated Electrons