Charge Density Refinement of the Si (111) 7x7 Surface

TL;DR

This study refines the local charge density of the Si (111) 7x7 surface using combined x-ray and electron diffraction techniques, revealing anti-bonding states and quantifying charge transfer, and compares findings with DFT calculations.

Contribution

It introduces an experimental method to refine charge density at the Si (111) 7x7 surface and provides new insights into charge states and transfer mechanisms.

Findings

Adatoms are in anti-bonding states with underlying atoms.

Charge transfer of 0.26(4) e- from adatoms to layers.

Experimental results are compared with DFT calculations.

Abstract

We report an experimental refinement of the local charge density at the Si (111) 7x7 surface utilizing a combination of x-ray and high energy electron diffraction. By perturbing about a bond-centered pseudoatom model, we find experimentally that the adatoms are in an anti-bonding state with the atoms directly below. We are also able to experimentally refine a charge transfer of 0.26(4) e- from each adatom site to the underlying layers. These results are compared with a full-potential all-electron density functional DFT calculation.