Hydrogen/silicon complexes in silicon from computational searches

TL;DR

This study uses density-functional theory to identify and analyze low-energy hydrogen/silicon defect complexes in crystalline silicon, discovering new defect structures with lower energies and higher symmetries than previously known.

Contribution

The paper introduces new defect structures involving hydrogen and silicon interstitials with lower energies and higher symmetries, expanding understanding of defect configurations in silicon.

Findings

Identified a new {I,H} defect with higher symmetry and lower energy.

Confirmed {I,H_2} as the most stable defect.

Discovered lower-energy structures for {I,H_3} and {I,H_4} defects.

Abstract

Defects in crystalline silicon consisting of a silicon self-interstitial atom and one, two, three, or four hydrogen atoms are studied within density-functional theory (DFT). We search for low-energy defects by starting from an ensemble of structures in which the atomic positions in the defect region have been randomized. We then relax each structure to a minimum in the energy. We find a new defect consisting of a self-interstitial and one hydrogen atom (denoted by {I,H}) which has a higher symmetry and a lower energy than previously reported structures. We recover the {I,H_2} defect found in previous studies and confirm that it is the most stable such defect. Our best {I,H_3} defect has a slightly different structure and lower energy than the one previously reported, and our lowest energy {I,H_4} defect is different to those of previous studies.