Physical Forces Responsible for Agglomeration of Silicon Nanowires Arrays Synthesized by Metal-Assisted Chemical Etching

The silicon nanowires (SiNWs) allow various application in a photovoltaic cell, including energy conversion and storage. However, the agglomeration or bunching of nanowires due to undesired functionalization elements is the major issue in the effective and efficient application of SiNWs. The work reports the effect of different forces on SiNWs during the natural drying process and the cause of agglomeration. The dependence of physical forces on the morphology of SiNWs, such as diameter, length, and intermediate gap, is demonstrated by assuming theoretical models. The vertically aligned SiNWs are synthesized by metal-assisted chemical etching (MACE) on a P-type Si wafer. A hydrophilic pre-treatment of HNO3 wash to remove Ag particles followed by a hydrophobic post-treatment of HF acid solution allows the synthesis of independent large and dense arrays of SiNWs. The work aims for various applications in self-cleaning solar cells, bio-adhesion, oil-water separation, energy conversion, and storage.