First-principles study of the Young's modulus of Si <001> nanowires

TL;DR

This study uses first-principles density functional theory to investigate how the Young's modulus and mechanical properties of hydrogen-passivated Si <001> nanowires depend on size, revealing surface effects dominate at small scales.

Contribution

It provides a detailed first-principles analysis of the size-dependent mechanical properties of Si <001> nanowires, comparing results with existing models.

Findings

Young's modulus scales with surface area to volume ratio.

Size dependence observed in equilibrium length and residual stress.

Results align with surface-dominated physical models.

Abstract

We report the results of first-principles density functional theory calculations of the Young's modulus and other mechanical properties of hydrogen-passivated Si <001> nanowires. The nanowires are taken to have predominantly {100} surfaces, with small {110} facets. The Young's modulus, the equilibrium length and the residual stress of a series of prismatic wires are found to have a size dependence that scales like the surface area to volume ratio for all but the smallest wires. We analyze the physical origin of the size dependence, and compare the results to two existing models.