The technique of impact-collision ion-scattering spectrometry was used to study the 4 x 1 reconstruction of In on the Si(111) surface. The top layer of adatoms was arranged in double-row ridges, with 3 equivalent orientations running in <1¯10> directions. Several models were simulated for both ½ML and 1ML coverages of the surface. The impact-collision ion-scattering spectrometry polar-angle scans did not agree with models containing substitutional In in the first Si layer. Instead, a ½ML model with In adatoms sitting in inequivalent sites provided the closest agreement with experiment. The vertical displacement between the In adatoms and the first Si layer was determined experimentally to be 1.15Å.

Si(111)-(4 x 1)In Surface Reconstruction Studied by Impact-Collision Ion-Scattering Spectrometry. D.M.Cornelison, M.S.Worthington, I.S.T.Tsong: Physical Review B, 1991, 43, 4051-6