We report on the scanning tunneling microscopy observation of small Si islands with a 1 x 1 termination on the Si(1 1 1) surface. The islands were prepared by thermal desorption of Tl from the Tl-terminated silicon sample by means of annealing to 400-600 degrees C. Structure of the islands is interpreted as the dimer-stacking-fault (DS) model. We propose that the otherwise unfavorable 1 x 1 termination is stabilized by subsurface dimers of DS. (C) 2009 Elsevier B. V. All rights reserved.