Surface structure of the 3x3-Si phase on Al(111), studied by the multiple usages of positron diffraction and core-level photoemission spectroscopy

TL;DR

This study combines positron diffraction and core-level photoemission spectroscopy to reveal that the 3x3-Si surface on Al(111) is a flat honeycomb lattice with embedded Al atoms, forming an Al-embedded silicene layer.

Contribution

It provides a detailed structural characterization of the 3x3-Si/Al(111) surface using combined experimental and first-principles methods, revealing the Al-embedded silicene structure.

Findings

The overlayer has a flat honeycomb lattice structure.

One Si atom is replaced by Al in the unit cell.

The surface forms an Al-embedded silicene layer.

Abstract

The structure of an Al(111)3x3-Si surface was examined by combining data from positron diffraction and core-level photoemission spectroscopy. Analysis of the diffraction rocking curves indicated that the overlayer had a flat honeycomb lattice structure. Simulations of Si core-level spectra calculated via the first-principles indicated that one of the Si atoms in the unit cell was replaced by an Al atom. The surface superstructure was thus a two-dimensional layer of Al-embedded silicene on Al(111).