Influence of pre-surface treatment on the morphology of silicon nanowires fabricated by metal-assisted etching

• Published in: Applied surface science Vol. 257; no. 6; pp. 1829 - 1834
• Main Authors: Shiu, Shu-Chia, Lin, Shin-Bo, Hung, Shih-Che, Lin, Ching-Fuh
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 2011; Elsevier
• Subjects: Antireflection; Arrays; Clusters, nanoparticles, and nanocrystalline materials; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density; Etching; Exact sciences and technology; Materials science; Metal-assisted etching; Nanoparticles; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanowires; Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity); Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Pre-surface treatment; Reflectance; Reflectivity; Silicon; Silicon nanowire; Silver; Structure of solids and liquids; crystallography; Surface cleaning, etching, patterning; Surface treatments; Pre-surface treatment; Metal-assisted etching; Antireflection; Silicon nanowire; Scanning electron microscopy; Hydrogen; Surface treatments; Etching; Surface structure; Reflectivity; Nanoparticles; Silver; Transition elements; Silicon; Nanowires; Pretreatment; Arrays; Nanostructured materials
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.08.086

Herein we demonstrate an improved metal-assisted etching method to achieve highly dense and uniform silicon nanowire arrays. A pre-surface treatment was applied on a silicon wafer before the process of metal-assisted etching in silver nitrate and hydrogen fluoride solution. The treatment made silver ion continuously reduce on silver nuclei adherence on the silicon surface, leading to formation of dense silver nanoparticles. Silver nanoparticles acting as local redox centers cause the formation of dense silicon nanowire arrays. In contrast, an H-terminated silicon surface made silver ion reduce uniformly on the silicon surface to form silver flakes. The silicon nanowires fabricated with a pre-surface treatment reveals higher density than those fabricated without a pre-surface treatment. The volume fraction improves from 18 to 38%. This improvement reduces the solar-weighted reflectance to as low as 3.3% for silicon nanowires with a length of only 0.87 μm. In comparison, the silicon nanowires fabricated without a pre-surface treatment have to be as long as 1.812 μm to achieve the same reflectance.