Morphological Control of Silicon Nanowire Arrays Formed by Metal-Assisted Chemical Etching Method

Abstract:

Control of the orientation and length of silicon nanowire (SiNW) arrays has been achieved in large-scale single-crystalline SiNW arrays fabricated by a metal-assisted chemical etching technique. Well-aligned vertical and slanted SiNW arrays with ultra-high aspect ratios have been successfully fabricated, yielding nanowires with lengths of approximately 110 µm and diameters ranging from 100 to 200 nm after 75 minutes of etching. This formation is attributed to the selective etching of the silicon surface directly in contact with Ag particles via a microscale electrochemical cell consisting of a metal catalyst, Si substrate, and etchant solution. Moreover, the effects of etching parameters (AgNO₃ concentration, etching time, and H₂O₂ concentration) and substrate properties (crystal orientation) on the as-prepared SiNWs have been systematically investigated. The results indicate that the morphology of the fabricated silicon nanostructures depends remarkably on AgNO₃ concentration. The length of SiNWs shows a linear dependence on the etching time (0-1 h). Fast SiNW formation with a rate of 1.7 µm min^-1 is achieved under optimized process conditions. However, the etching rate decreases slowly for long etching times (>1 h). Substrate properties have a direct relation to the SiNW orientation. By variation of the H₂O₂ concentration, inclined or vertical etching can be achieved on Si(111) substrates. SiNWs can be understood on the basis of the self-assembled localized microscopic electrochemical cell model. Finally, the optical properties of SiNWs etched in solutions with different concentrations of H₂O₂ have also been discussed.

• Periodical: Journal of Nano Research (Volume 91)
• Pages: 15-33
• DOI: https://doi.org/10.4028/p-3nQfup
• Online since: March 2026
• Authors: Shi Ying Zhang*, Du Shuai Wei, Bo En Zhang, Bo Yuan Yang, De Fu Sun, Hui Dong Yu, Kai Ze Jiang, Ben Fa Wang, Yu Zhu Wu, Zhong Xin Wang, Qiu Bo Li, Li Huan Wang, Lei Zhang, Guo Dong Wang, Shou Zhi Wang, Yu Zhang, Qing Jun Xu
• Keywords: Crystallographic Etching, Etching Kinetics, Nanowire Morphology, Structural Porosity

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