DIRECT OBSERVATION OF SB DIMERS ON INSB(100)-C(4X4)

Scanning tunneling microscopy (STM) has been used to investigate the structure of the Sb-terminated InSb(100)-c(4 X 4) surface formed by deposition of Sb onto an In-terminated c(8 X 2) surface. Rectangular blocks of three Sb dimers are observed, with the dimer bond aligned along the [011BAR] direction. The images are consistent with a structure based on a missing dimer model, in which a 3/4 monolayer of Sb atoms in the top layer form dimers on top of a full monolayer Sb-terminated surface. Atomically well resolved filled and empty states images of this surface show identical features and indicate that the same species, namely the Sb dimer, is imaged at both negative and positive sample bias.