Fe-silicide nanostructures on Si(111)-3×3-Ag

Abstract

Scanning tunneling microscopy was used to investigate the influence of Ag-induced surface reconstructions on the formation of low-dimensional Fe-Si structures. The deposition of 1Å Fe (i.e., 1.1 monolayer) at 300°C on the 3×1-Ag, the 3×3-Ag, and the 7×7 reconstructions of the Si(111) surface results in the self-assembly of small islands. For both Ag-induced reconstructions, these islands are significantly larger compared to those formed on the Si(111)-7×7 surface due to an increased surface diffusion. Moreover, on the 3×3 structure, these nanodots are well separated and in between, the initial reconstruction remains unchanged. In the presence of surface steps, these islands preferentially nucleate at the lower step edge, which can be used to grow long continuous nanowires for higher Fe coverage and vicinal surfaces. Furthermore, from the phenomena such as step retraction and island/hole combinations, it is concluded that these nanostructures consist of Fe-silicide.