Phosphorus donors in highly strained silicon

TL;DR

This study investigates how high strain in silicon affects phosphorus donor hyperfine interactions, revealing reductions beyond theoretical predictions due to lattice effects, with implications for quantum computing.

Contribution

It provides experimental measurements of hyperfine interactions in strained silicon and explains the reduction using DFT and Green's function models, advancing understanding of donor behavior under strain.

Findings

Hyperfine interactions as low as 0.8 mT in highly strained silicon

Reduction exceeds valley repopulation predictions

DFT shows volume increase and ligand relaxation cause the reduction

Abstract

The hyperfine interaction of phosphorus donors in fully strained Si thin films grown on virtual Si$_{1-x}$Ge$_x$ substrates with $x\leq 0.3$ is determined via electrically detected magnetic resonance. For highly strained epilayers, hyperfine interactions as low as 0.8 mT are observed, significantly below the limit predicted by valley repopulation. Within a Green's function approach, density functional theory (DFT) shows that the additional reduction is caused by the volume increase of the unit cell and a local relaxation of the Si ligands of the P donor.