Evidence for trimer reconstruction of Si(111) 3 × 3 -Sb: Scanning tunneling microscopy and first-principles theory

Scanning-tunneling-microscopy images of the Si(111) 3 × 3 -Sb surface show a trigonal lattice of protrusions, with a characteristic dependence on bias voltage. When probing filled surface states, the protrusions consist of three topographic maxima, while probing empty surface states gives a single maximum. These observations are interpreted in terms of an Sb-trimer model, the structure of which is obtained through first-principles calculations. Charge-density contours show that the three maxima seen when probing filled states can be directly related to the positions of the Sb-trimer atoms. © 1990 The American Physical Society.