Correlation Between Oxidant Concentration and Morphological Properties of Silicon Nanowires Obtained by Silver-Assist Electroless Etching

In this work, a correlation between oxidant concentration and the morphological changes of silicon nanowires formed by a two-step silver-assist electroless etching method is established. It reveals that a textured silicon surface appears for samples etched at relatively H2O2 concentration lower than 2%. However, The dynamic and kinetics of silicon nanowires for different H2O2 concentration (5%, 7% and 8%) are studied by scanning electron microscopy. We found that the thickness of etched silicon nanowires as a function of time fallows a linear law. The length of silicon nanowires is not only H2O2 concentration dependent but a critical is necessary to overcome length saturation. We prove also that the oxidation rate of silicon facing Ag particles can limit the dynamic of wire formation, due to the generation of silicon hexafluoride ion (SiF6)2-.