Fig.12 Dense and Dilute Row Fundamental Units. The top feature imaged is a dilute row and the bottom feature is a dense row. The dilute row may be regarded as a chain of type C dimers plus two monomers, or a cross plus a dimer at one end. It images as a pair of crosses. Since the Si (001)-2 × 1 reconstructed surface is built of dense rows; the properties of such rows is of great interest to those studying silicon growth. For the same reason, if and how dilute rows evolve into dense ones are also interesting questions.

Fig.13 Filled vs. Empty State Images of a Dilute Row. The empty state image reveals the end monomers depicted in Fig. 12's diagram.

Fig.14 Filled vs. Empty State Images of a Dense Row. Focusing on the end of a dense row (which extends out of the image to the right), one can see the lengthwise splitting of the row in the empty state image. This reflects the orientation of the two dangling bonds of each of the dimers which comprise the row. These dangling bonds are depicted in the schematics of Figs.1A and B. The slight skewing of the image is due to sample drift during imaging.

Fig. 15. Tie-Cross-Dense Row Conversion. The first two steps of this short involve an A to C-dimer conversion, and back. Unlike with the Stealth conversion in Fig. 5, the central dimer is accompanied by two monomers which presumably anchor it and prevent diffusion along the row. In the last step another pair of atoms joins the original four and a dense row is formed. The procession of configurations is Tie to Cross to Tie to Dense Row. More images and information about the Tie and Cross configurations are available on the Two Dimer Configurations page of the Gallery. This is an excerpt from a longer movie that will be available for viewing at a later date. Image Rate= 1/min.; Temperature= 441K.