First-principles study of the atomic and electronic structure of the Si(111)-(5x2-Au surface reconstruction

TL;DR

This study uses first-principles calculations to analyze various structural models of the Si(111)-(5x2)-Au surface reconstruction, identifying the most stable configurations and comparing their electronic properties with experimental data.

Contribution

It introduces a new atomic model for the Si(111)-(5x2)-Au surface and compares its stability and electronic structure with existing models using density functional theory.

Findings

The new model is most stable at low adatom concentrations.

Erwin's model becomes favorable at higher adatom concentrations.

Both models align well with experimental photoemission data.

Abstract

We present a systematic study of the atomic and electronic structure of the Si(111)-(5x2)-Au reconstruction using first-principles electronic structure calculations based on the density functional theory. We analyze the structural models proposed by Marks and Plass [Phys. Rev. Lett.75, 2172 (1995)], those proposed recently by Erwin [Phys. Rev. Lett.91, 206101 (2003)], and a completely new structure that was found during our structural optimizations. We study in detail the energetics and the structural and electronic properties of the different models. For the two most stable models, we also calculate the change in the surface energy as a function of the content of silicon adatoms for a realistic range of concentrations. Our new model is the energetically most favorable in the range of low adatom concentrations, while Erwin's "5x2" model becomes favorable for larger adatom concentrations. The crossing between the surface energies of both structures is found close to 1/2 adatoms per 5x2 unit cell, i.e. near the maximum adatom coverage observed in the experiments. Both models, the new structure and Erwin's "5x2" model, seem to provide a good description of many of the available experimental data, particularly of the angle-resolved photoemission measurements.