We have investigated the Sb-induced reconstruction of the Si(112) surface using low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). Upon Sb adsorption on the clean reconstructed Si(112) surface at 300 degrees C, the Si(112)-(111)1 X 1-Sb surface was obtained. The present STM study gathered the following findings: The Sb-adsorbed Si(112) surface is composed of saw toothlike nanofacets, which are composed of the (557) plane and the (111) plane. The (557) plane consists of about five (111) planes with five times the width of bulk-terminated (111) 1X1 unit cell and (001) plane. It is also about 8.5 angstrom in height and tilted at a 9.9 degrees angle with respect to the basal plane (112). Based on observation, it appears that the Sb atoms on the (111) planes substitute for the topmost Si atoms on the ideal Si(111) 1 X 1 surface. Based on the STM results, we suggest a structural model and discuss the reconstructing mechanism of nanofacets induced by Sb adsorption. (c) 2005 American Vacuum Society.