First-principles study on field evaporation for silicon atom on Si(001) surface

TL;DR

This study uses first-principles simulations to analyze field evaporation of silicon atoms on Si(001) surfaces, revealing the electric field thresholds and the importance of bond strength over local field effects.

Contribution

It provides a first-principles computational insight into the electric field-induced atom evaporation process on Si(001) surfaces, aligning with experimental data.

Findings

Atoms on flat and stepped Si(001) surfaces are easily evaporated under electric fields.

Threshold electric field for evaporation is between 3.0 and 3.5 V/Å, matching experimental results.

Local field effects are less important than bond strength in atom evaporation.

Abstract

The simulations of field-evaporation processes for silicon atoms on various Si(001) surfaces are implemented using the first-principles calculations based on the real-space finite-difference method. We find that the atoms which locate on atomically flat Si(001) surfaces and at step edges are easily removed by applying external electric field, and the threshold value of the external electric field for evaporation of atoms on atomically flat Si(001) surfaces, which is predicted between 3.0 and 3.5 V/\AA, is in agreement with the experimental data of 3.8 V/\AA. In this situation, the local field around an evaporating atom does not play a crucial role. This result is instead interpreted in terms of the bond strength between an evaporating atom and surface.