Structural Examination of Au/Ge(001) by Surface X-Ray Diffraction and Scanning Tunneling Microscopy

TL;DR

This study combines surface X-ray diffraction and scanning tunneling microscopy to analyze the atomic structure of Au/Ge(001), revealing detailed atomic arrangements and the roles of Au-Ge and Au-Au dimers in the reconstruction.

Contribution

It provides a comprehensive structural model of Au/Ge(001) by integrating SXRD, STM, and DFT, identifying specific atomic configurations and non-equivalent Au positions.

Findings

Identification of three non-equivalent Au positions within the c(8x2) unit cell.

Confirmation of Au-Ge hetero-dimers and Au-Au homo-dimers as structural building blocks.

Correlation of interatomic distances with both SXRD and STM data.

Abstract

The one-dimensional reconstruction of Au/Ge(001) was investigated by means of autocorrelation functions from surface x-ray diffraction (SXRD) and scanning tunneling microscopy (STM). Interatomic distances found in the SXRD-Patterson map are substantiated by results from STM. The Au coverage, recently determined to be 3/4 of a monolayer of gold, together with SXRD leads to three non-equivalent positions for Au within the c(8x2) unit cell. Combined with structural information from STM topography and line profiling, two building blocks are identified: Au-Ge hetero-dimers within the top wire architecture and Au homo-dimers within the trenches. The incorporation of both components is discussed using density functional theory and model based Patterson maps by substituting Germanium atoms of the reconstructed Ge(001) surface.