Si(111)-5×1-Au reconstruction as studied by scanning tunneling microscopy

Scanning tunneling microscopy (STM) is used to characterize the Si(111)-5×{}1-Au surface reconstruction that occurs at 0.4 monolayers Au. We observe three equivalent domains of the 5×{}1 structure, which appear as rows oriented along 〈1{}10〉 directions with a five-unit-cell separation. STM images reveal an asymmetric structure with a two-unit-cell periodicity along any given row. The phase of this two-unit-cell periodicity is not correlated between rows, however, preventing any long-range 5×{}2 order. In addition, bright features are commonly seen along the 5×{}1 rows, always located at multiples of the two-unit-cell spacing.