Constructing silicon nanotubes by assembling hydrogenated silicon clusters

TL;DR

This study uses density functional calculations to design and analyze hydrogenated silicon nanotubes assembled from silicon clusters, revealing their stability, electronic properties, and potential for electronic applications.

Contribution

It introduces a systematic method to construct stable silicon nanotubes from hydrogenated silicon clusters and analyzes their stability and electronic properties.

Findings

Stable silicon nanotubes can be assembled from hydrogenated silicon clusters.

Certain nanotubes exhibit large energy gaps and potential for electronic devices.

The band gap transitions from direct to indirect with increasing tube radius.

Abstract

The search or design of silicon nanostructures similar to their carbon analogues has attracted great interest recently. In this work, density functional calculations are performed to systematically study a series of finite and infinite hydrogenated cluster-assembled silicon nanotubes (SiNTs). It is found that stable one-dimensional SiNTs with formula $Si_{m(3k+1)}H_{2m(k+1)}$ can be constructed by proper assembly of hydrogenated fullerene-like silicon clusters $Si_{4m}H_{4m}$. The stability is first demonstrated by the large cohesive energies and HOMO-LUMO gaps. Among all such silicon nanotubes, the ones built from $Si_{20}H_{20}$($m=5$) and $Si_{24}H_{24}$($m=6$) are the most stable due to the silicon bond angles that are most close to the bulk $sp^{3}$ type in these structures. Thermostability analysis further verifies that such tubes may well exist at room temperature. Finally, both finite nanotubes and infinite nanotubes show a large energy gap. A direct-indirect-direct band gap transition has been revealed with the increase of the tube radius. The existence of direct band gap may make them potential building blocks for electronic and optoelectronic devices.