Scanning tunneling microscopy
(STM) has provided many breakthroughs in imaging surfaces on atomic scale.
Some of the most notable of these have been for the crystalline (100) surface
of sillicon, which has great technological importance and also serves as
the model semiconductor system for studying atomistic growth mechanisms
and electronic properties. The STM image on the left reveals a Si(100)
surface which is miscut by a few degrees. The surface reconstructs forming
rows of sillicon atom pairs (called dimers) on terraces separated by atomic
layers. Three main terraces are shown with dimers running perpendicular
to the double-layer steps. The mean terrace width is approximately 4 nanometers.
As the dimensions of artificially structured materials decrease (imagine,
if the size of a device grown on the Si surface approaches nanometer-scale),
the role of the interfaces becomes increasingly important in determining
physical and electronic properties.
------ The image has been
chosen for inclusion in "Physics in the 20th Century", the
commemorate issue of the centennial of American Physical Society. For details,
Phys. Rev. Lett. 84, 4546-4549