Recession and Characterization of Patterned Nanowires Grown by Electroless Etching of Silicon

Abstract

Silicon nanowires (SiNWs) were grown by the electroless etching technique using silver nitrate (AgNO3)/hydrofluoric acid (HF) solution on a patterned p-type Silicon (Si) substrate with varying etching times and concentrations. The various etch times and concentrations produced different recession depths wherever the pattern allowed the etching solution to contact the Si substrate. At the bottom of each recession, SiNWs were produced of varying length and size, according to the depth of the recession. In this type of growth procedure, as SiNWs are grown, the tips are etched away. SiNWs grown by this method tend to agglomerate at their tips. We report that the recession and height of SiNWs grown by the electroless process can be controlled directly by the concentration of HF in the etching solution and by the etching time. Under precise conditions, the recession of SiNWs can be very nearly eliminated or nearly complete. The heights of SiNWs can also be fairly well controlled. We report that the growth of SiNWs is highly dependent on the ratio of volume of etching solution to the exposed surface area.