Stable fourfold configurations for small vacancy clusters in silicon from ab initio calculations

TL;DR

This paper uses density-functional-theory calculations to identify new, more stable fourfold configurations for small vacancy clusters in silicon, challenging previous assumptions about their lowest-energy states.

Contribution

It introduces novel stable configurations for vacancy clusters in silicon that have lower formation energies than previously known structures.

Findings

New stable configurations with lower formation energies identified

Configurations consist of a ring-hexavacancy with interstitial atoms

Lower formation energies by 0.6 to 1.0 eV compared to previous models

Abstract

Using density-functional-theory calculations, we have identified new stable configurations for tri-, tetra-, and penta-vacancies in silicon. These new configurations consist of combinations of a ring-hexavacancy with three, two, or one interstitial atoms, respectively, such that all atoms remain fourfold. As a result, their formation energies are lower by 0.6, 1.0, and 0.6 eV, respectively, than the ``part of a hexagonal ring'' configurations, believed up to now to be the lowest-energy states.