Observation of sulfur-terminated GaAs(001)-(2×6) reconstruction by scanning tunneling microscopy

Scanning tunneling microscopy (STM) images of smooth, in situ prepared, sulfur-terminated (S-terminated) GaAs(001) surface reconstruction are presented. It is found that (2×6) surface reconstruction is dominant on the S-terminated GaAs(001) surface. This (2×6) reconstruction, of which the cell contains five S-S adatom dimers, is determined by both STM and reflection high-energy electron diffraction. The atomic model, which is consistent with both STM images and electron counting heuristics, is also shown. Moreover, this (2×6) reconstruction is also observed in the case of an (NH4)2Sx-treated surface.