STM observation of initial growth of Sn atoms on Ge(001) surface

TL;DR

This study uses scanning tunneling microscopy to investigate how tin atoms initially grow on germanium surfaces at different temperatures, revealing the formation of specific one-dimensional structures and the influence of surface strain.

Contribution

It provides new insights into the initial growth mechanisms of Sn on Ge(001), highlighting the role of diffusion barriers and surface strain in structure formation.

Findings

Sn atoms form two types of one-dimensional ad-dimer structures at room temperature.

At 80 K, the population of <310>-aligned dimer chains increases.

Surface strain influences the diffusion barrier and structure formation.

Abstract

We have studied initial growth of Sn atoms on Ge(001) surfaces at room temperature and 80 K by scanning tunneling microscopy. For Sn deposition onto the Ge(001) substrate at room temperature, the Sn atoms form two kinds of one-dimensional structures composed of ad-dimers with different alignment, in the <310> and the <110> directions, and epitaxial structures. For Sn deposition onto the substrate at 80 K, the population of the dimer chains aligning in the <310> direction increases. The diffusion barrier of the Sn adatom on the substrate kinetically determines the population of the dimer chain. We propose that the diffusion barrier height depends on surface strain induced by the adatom. The two kinds of dimer chains appearing on the Ge(001) and Si(001) surfaces with adatoms of the group-IV elements are systematically interpreted in terms of the surface stain.