Controlled Fabrication of Wafer-Scale Zigzag Silicon Nanowire Arrays by Metal-Assisted Chemical Etching through Synergistic Effect of Viscosity and Temperature

Zigzag silicon nanowires (SiNWs) attract great interest due to their unique physical/chemical properties that make them appealing in various applications; yet, their fabrication has always been difficult and the formation mechanism for zigzag silicon nanostructures remains elusive. In this work, the influence of temperature on the morpholohies of SiNWs by metal-assisted chemical etching (MatEtch or MACE) in aqueous HF-H2O2-C3H8O3 solution is systematically analyzed. It is found that zigzag-shaped silicon nanowires can be fabricated through a slow etching process at low temperatures in the presence of glycerol (C3H8O3). The synergistic effect of glycerol and low etchant-temperatures varied from 15 degrees C to 35 degrees C facilitate the fabrication of zigzag-SiNWs. The arm length of the zigzag design increases with the increase of temperature. However, straight SiNWs are fabricated at higher temperatures, such as those greater than 35 degrees C. It is also shown that for dispersed AgNPs, straight channels can be obtained at higher temperatures, while low temperature favors zigzag channels with decreasing arm length. We anticipate that these findings provide scientific guidance for the controlled fabrication of large-scale zigzag SiNW arrays.