FIM tips in SPM: Apex orientation and temperature considerations on atom transfer and diffusion

TL;DR

This study investigates how apex orientation and temperature influence atom transfer and diffusion on tungsten tips in STM, highlighting the importance of tip structure and temperature in maintaining atomic precision.

Contribution

It provides new insights into how tip orientation and temperature affect atom transfer and diffusion, guiding better tip preparation for atomic-scale STM studies.

Findings

W(111) tips are more suitable for atomic-scale characterization.

Diffusion activation energies vary between (111) and (110) planes.

Temperature significantly impacts atomic structure stability.

Abstract

Atoms transferred to W(111) and W(110) tip apices from the Au(111) surface during tunneling and approach to mechanical contact experiments in STM are characterized in FIM at room temperature and at 158 K. The different activation energies for diffusion on the (111) and (110) tip planes and the experiment temperature are shown to be important factors controlling the extent of changes to the atomic structure of the tip. W(111) tips are much better suited to scanning probe studies which require the characterization of an atomically defined tip and subsequent verification of its integrity in FIM. The statistics of the observed spikes in the tunneling current when the tips are approached to Au(111) are interpreted using a simple model of adatoms diffusing through the STM junction.