Molecular and Electronic Tuning of Si/Carbon Nanotube Hybrid System

In complex structures such as conjugated Si nanoparticles on carbon nanotubes (CNT), new properties arise out particle size control or nanoparticle--nanotube contact. In this work, the interaction of Si clusters (Sin, $n=1{\mbox{--}}4$) with metallic $(5,5)$ single-wall carbon nanotube (SWCNT) is investigated using first principles calculations based on density functional theory, to show that electronic property of the Si/SWCNT system can change via Si--SWCNT conformation alone. Planar Si clusters on SWCNT exhibit the same metallic property regardless of size. However, once the planarity of Sin is lost, which happens when Si adsorption sites shifts towards the top and the Si--C bonds bend resulting to a buckled Sin configuration, a band gap of ${\sim}0.32$ eV in the entire Si/SWCNT system is introduced. The migration behavior of Si adatoms shows ease of cluster formation due to surface curvature. Such cluster formation can be accommodated by a distortion in the C--C bonds of CNT. Mechanism for the opening of the SWCNT band gap is presented.