Preparation and characterization of silicon nanowires catalyzed by aluminum

Silicon nanowires (SiNWs) were grown on indium tin oxide coated glass substrates by a pulsed plasma-enhanced chemical vapor deposition (PPECVD) method using aluminum as a catalyst. The thin films of the catalyst, with thicknesses ranging from 10 nm to 100 nm, were deposited on the substrates by thermal evaporation. The effect of the thickness of the thin film catalyst on the morphology of the silicon nanowires was investigated. The surface morphology study of the prepared wires showed that the modal wire diameter increased as the catalyst film thickness increased. The X-ray diffraction patterns of the prepared silicon nanowires had no silicon peaks, indicating that the wires had low crystallinity. The photoluminescence spectra of the SiNWs showed that all samples had more than one emission band. The emission band location and shape were found to be dependent on catalyst thickness. The Raman spectra of the prepared nanowires showed that the first order transverse band shifted toward lower frequencies compared with the c-Si band location.