Formation of indium arsenide atomic wires on the In/Si(111)-4 x 1 surface

Density functional theory calculations have been applied to describe the formation of InAs atomic-size wires on the In/Si(111)-4 x 1 surface. Two different coverages, 1/4 ML and 1/2 ML, were considered. We have taken in to consideration different high symmetry sites for As adsorption. At 1/4 ML coverage, in the energetically stable configuration, As and In atoms form atomic wires. Upon increasing the coverage up to 1/2 ML of As, a pair of InAs atomic wires are formed. Surface formation energy calculations help to clarify the stability ranges of these structures: for arsenic poor conditions the stable configuration corresponds to the In/Si(111)-4 x 1 surface (with no As atoms). Increasing the arsenic content, for intermediate to rich As conditions, results in the formation of an InAs wire. At the arsenic rich limit, the formation of two InAs wires is favorable. The InAs wires are highly symmetric, and charge density distributions and projected density of states show the covalent character of the In As bonds of the wire. These results demonstrate that the In/Si(111)-4 x 1 surface may be used as a substrate to growth quasi-unidimensional InAs wires. (C) 2017 Elsevier Ltd. All rights reserved.