  We consider the interplay between superconducting coupling and dopant
impurity scattering of charge carriers in planar square lattice systems and
examine physical conditions (doping level, temperature, local symmetry of
coupling and scattering potentials) necessary in this model system to obtain a
d-wave superconducting order, like that observed in real doped cuprate HTSC
materials. Using the Lifshitz model for the disorder introduced into system by
dopants, we analyze also the non-uniform structure of such d-wave parameter,
including both its magnitude and phase variation. The results indicate that
d-wave superconductivity turns possible in a doped metal until it can be
destroyed at too high doping levels.
