Forest of ultra thin silicon nanowires: realization of temperature and catalyst size

Abstract

One of the most important progresses in the field of nano science and technology was partially due to the high surface to volume ratio of quasi one-dimensional silicon nanowires (SiNWs) with various applications in biological and chemical sensors, optoelectronic devices, catalysis, Li ion batteries and solar cells. In this study we have prepared a uniform forest of ultrathin SiNWs using plasma enhanced chemical vapor deposition method. Uniformly distributed SiNWs were obtained based on an Au layer containing gold nano-seeds with the average diameters ranging from 10 to 40 nm at various temperatures. The physicochemical properties of SiNWs were characterized using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), photoluminescence (PL) and high-resolution transmission electron microscopy. Microscopic assessments revealed that crystalline-amorphous core–shell SiNWs with different diameters and lengths ranging from 35 to 130 nm and ~ 0.7 to 1.9 µm are formed during the vapor–liquid–solid mechanism, respectively. The XRD spectra show that the main lattice directions are Si(111), Si(220) and Si(311) which confirm crystalline structure of synthesized NWs. The PL spectrum reveal two distinct emission peaks at wavelengths of about 480 nm (blue range) and 690 nm (red range) as sharp and a broad peak, respectively.