Becky Cook's jmol
series
page I
Here's a silicon nanocube, one of whose surfaces has been
cut off so that it is no longer parallel to the cubic lattice.
If you look at it from an appropriate direction,
parallel to the surface, you see plateaus on the surface
associated with alternating dimer rows.
Click here
for an interactive version of the same nanosilicube model, more clearly
labeled with help from a different applet.
Below find an atomic force microscope image of dimer row steps
nearly 1000 Angstroms (0.1 microns) apart on a silicon surface,
resulting from a "miscut angle" of about 0.08 degrees sloping
at an angle of about 45 degrees to both of the alternating dimer
row layers. If the miscut slopes perpendicular to one of the
dimer rows, one sees parallel steps corresponding to that row
separated by zigzag or even invisible steps corresponding to
the alternate row.
Note that the vertical scale in the image (from dark to bright)
is only 5 Angstroms. This may be a clue to the answer for the
question above.