Effect of surface treatment on photoluminescence of silicon carbide nanotubes

Abstract

SiC nanotubes were synthesized by the reaction of multi-walled carbon nanotubes (MWCNTs) with Si powder. In order to eliminate any remaining elemental carbon in the nanotubes and unreacted MWCNTs, heat treatments were carried out in air at various temperatures. The evaluated characterization in this study are relative to the SiC nanotubes after heat treatment in air. Photoluminescence (PL) spectra of SiC nanotubes with and without alkali and acid treatments were evaluated at room temperature by microspectroscopy. The PL spectrum of the SiC nanotubes heat treated at 700°C consisted of a dominant peak around 2.5eV, while no definite peak was observed in the PL spectra of those heat treated at 800 and 900°C. The reason is believed to be that SiO2 layers were produced on the surface of the SiC nanotubes. Treatment by NaOH followed by HCl solution was carried out to remove the SiO2 layers after the heat treatment. The results show that stronger PL bands emerged after the NaOH-HCl treatment. From these results, we conclude that the PL bands of SiC nanotubes are closely related to their surface state and surface defects.