Density functional theory calculations of the stress of oxidised (110) silicon surfaces

TL;DR

This paper uses density functional theory to calculate surface stress on oxidized silicon surfaces, revealing higher values than previously assumed, which could impact precise lattice parameter measurements.

Contribution

It introduces a DFT-based approach to quantify surface stress on oxidized silicon surfaces, improving understanding of intrinsic strains affecting measurements.

Findings

Surface stress exceeds previous estimates

Potential impact on silicon lattice parameter measurements

DFT provides a more accurate stress quantification

Abstract

The measurement of the lattice-parameter of silicon by x-ray interferometry assumes the use of strain-free crystals. This might not be the case because surface relaxation, reconstruction, and oxidation cause strains without the application of any external force. In a previous work, this intrinsic strain was estimated by a finite element analysis, where the surface stress was modeled by an elastic membrane having a 1 N/m tensile strength. The present paper quantities the surface stress by a density functional theory calculation. We found a value exceeding the nominal value used, which potentially affects the measurement accuracy.