Metal-assisted electroless etching of silicon in aqueous NH4HF2 solution

► A non-HF based solution was developed to elaborate different shapes of Si nanostructures by the metal-assisted chemical etching process. ► Metal-assisted electroless etching of silicon was investigated in new chemical solution containing NH4HF2. ► It was shown that silicon nanowires are fabricated either by one-step or two-step metal-assisted chemical etchings. ► It was shown that the increase of NH4HF2 in the etching solution leads to the increase of etching rate.