We use atom-resolved scanning tunneling microscopy to evidence the formation of carbon atomic chains on the C-terminated $\beta -\mathrm{SiC}\left(100\right)$ surface. These carbon atom lines, which exhibit an extremely high thermal stability (up to $\approx 1200°\mathrm{C}$), comprise buckled single bond $\mathrm{C}—\mathrm{C}$ dimers $\left({\mathrm{sp}}^3\right)$ having a direction perpendicular to the $\mathrm{C}\equiv \mathrm{C}$ triple bond dimers $\left(\mathrm{sp}\right)$ forming a $c(2\times 2)$ surface reconstruction. Their presence does not result in/or from surface antiphase boundaries, and their density increases with annealing time. The results suggest anisotropic (tensile and compressive) surface stress as a leading driving force in this carbon $\mathrm{sp}\to {\mathrm{sp}}^3$ diamondlike temperature controlled transformation.

• Received 6 July 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.5868