  Scattering of a 2D Dirac electrons on a rectangular matrix potential barrier
is considered using the formalism of spinor transfer matrices. It is shown, in
particular, that in the absence of the mass term, the Klein tunneling is not
necessarily suppressed but occurs at oblique incidence. The formalism is
applied to studying waveguiding modes of the barrier, which are supported by
the edge and bulk states. The condition of existence of the uni-directionality
property is found. We show that the band of edge states is always finite with
massless excitations, while the spectrum of the bulk states, depending on
parameters of the barrier, may consist of the infinite or finite band with
both, massive and massless, low-energy excitations. The effect of the Zeeman
term is considered and the condition of appearance of two distinct energy
dependent directions corresponding to the Klein tunneling is found.
