Peculiarities of Al magic cluster self-assembly on Si(100) surface

Using scanning tunneling microscopy observations and density functional theory calculations, regularities of the Al magic cluster array self-assembly on Si(100) surface has been elucidated. While a single Al cluster occupies an area of 4a x 3a, an ordered Al-cluster array exhibits a 4 x 5 periodicity, as the clusters in the array are separated by the 4a x 2a "spacers". The plausible structural model for the "spacer" was proposed in which the "spacer" is arranged as an ordinary 4a x 3a-Al cluster in which the central atomic row with the topmost Si atom is missing. Appearance of the "spacers" in the Al-cluster array was found to reduce formation energy of the array. Ability to incorporate the rows of Al-"spacers" into the completed 4 x 3 In-cluster array was demonstrated. (C) 2010 Elsevier B.V. All rights reserved.