Hydrogen/nitrogen/oxygen defect complexes in silicon from computational searches

TL;DR

This study uses density-functional theory and ab initio Random Structure Searching to identify and analyze low-energy hydrogen, nitrogen, and oxygen defect complexes in silicon, revealing new structures and formation energies.

Contribution

The paper introduces new low-energy defect structures in silicon involving H, N, and O, identified through computational searches, expanding understanding of defect configurations.

Findings

New lowest-energy defect structures identified

Comparison of defect formation energies with different oxygen potentials

Analysis of defect relative abundances in silicon

Abstract

Point defect complexes in crystalline silicon composed of hydrogen, nitrogen, and oxygen atoms are studied within density-functional theory (DFT). Ab initio Random Structure Searching (AIRSS) is used to find low-energy defect structures. We find new lowest-energy structures for several defects: the triple-oxygen defect, {3O}, triple oxygen with a nitrogen atom, {N, 3O}, triple nitrogen with an oxygen atom, {3N,O}, double hydrogen and an oxygen atom, {2H,O}, double hydrogen and oxygen atoms, {2H,2O} and four hydrogen/nitrogen/oxygen complexes, {H,N,O}, {2H,N,O}, {H,2N,O} and {H,N,2O}. We find that some defects form analogous structures when an oxygen atom is replaced by a NH group, for example, {H,N,2O} and {3O}, and {H,N} and {O}. We compare defect formation energies obtained using different oxygen chemical potentials and investigate the relative abundances of the defects.