Controllable growth of silicon nanowire arrays fabricated by two-step silver catalyzed chemical etching

Silicon nanowire arrays (SiNWs) were prepared by the two-step silver catalyzed chemical etching process. The influence of various factors such as deposition time of silver nanoparticles, etching process and post-treatment conditions on the morphology and structure of SiNWs were systematically investigated. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Ultraviolet-Visible spectroscopy (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the SiNWs. The results revealed the existence of a positive linear relationship between length and etching time, which could be used to control the length of the SiNWs. The length and diameter of the nanowires both gradually decreased as the duration of the post-treatment process increased. SiNWs can be obtained with better uniformity by optimizing the post-treatment duration. In addition, four different lengths of SiNWs with regular and uniform morphology were fabricated using the above controllable growth process. The results showed that the silver catalyst was completely removed after the as-obtained SiNWs were immersed into HNO3. All the as-prepared SiNWs showed a good light reflection performance, which was enhanced with increasing lengths of the arrays. The reflectance of the as-obtained SiNWs was found to be less than 1% within the range of the visible spectrum (300-800 nm). These results confirm that this simple fabrication method can help achieve controllable growth of SiNWs of desired sizes.