Figure 1: Atomic geometry of Sn/SiC(0001).
From: Nature of the Insulating Ground State of the Two-Dimensional Sn Atom Lattice on SiC(0001)
Top (a) and side (b) views of the structure of Sn/SiC(0001). The dashed line indicates the 
unit cell. The x, y, and z axes point along the [1000], 
, and [0001] directions, respectively. The large, medium, and small circles represent Sn, Si, and C atoms, respectively. For distinction, Sn atoms on the different y positions are drawn with dark and bright circles in the side view.
