Single-Layer of Bi1–xSbx Grown on Ag(111)

Abstract

In this work, we report the growth of a mixed Bi_1–x Sb_x single layer on the Ag(111) surface with various stoichiometries. The atomic geometry has been thoroughly investigated by low-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy experiments, as well as calculations based on density functional theory. We first determined that the Sb/Ag(111) system for coverages below 2/3 monolayer behaves similarly to the Bi/Ag(111) system, with a dealloying transition to a rectangular (3 × √3) phase when the Sb coverage exceeds 1/3 monolayer. We found two alternative preparation strategies to obtain a mixed Bi_1–x Sb_x layer: sequential deposition and simultaneous deposition of Bi and Sb. In the first case, one of the elements is deposited on a completely covered surface alloy of the other element. The obtained phase corresponds to a single mixed BiSb layer free of Ag atoms, forming a rectangular (3 × √3) structure. The simultaneous deposition strategy yields the same structure but offers the significant advantage of enabling controlled variation of the stoichiometry. The obtained mixed Bi–Sb phase has a lateral atomic arrangement very similar to the one in the nonalloyed phase observed for Sb on Ag(111), with Sb and Bi atoms distributed disorderly, and presents a significant vertical corrugation, promising considerable Rashba effects.