Effect of etching time on morphological, optical and structural properties of silicon nanowire arrays etched on multi-crystalline silicon wafer

In this work we report a rapid, cost effective and easy approach to prepare an antireflective surface by using silver assisted chemical etching method to form silicon nanowire arrays on multicrystalline silicon (mc-Si) wafer. We present a correlation between morphological, optical and structural properties of the obtained nanostructured mc-Si. We found that the length of silicon nanowires increases with increasing etching time. Beyond 30 min the wires are broken. This behavior is due to the existence of defects in multicrystalline silicon which facilitate the etching of the nanowires. AFM and SEM show the change of the morphology of the samples before and after the chemical etching. We investigate that the reflectivity of the nanowires etched for 30 min decreases to less than 3% which is beneficial for solar light trapping. Furthermore, we explore the role of etching time in the enhancement of Raman signal. We deduce that etching time plays a key role on the morphological, optical and structural properties of silicon nanowires.