Metal-Catalyzed Electroless Etching of Silicon in Aerated HF/H₂O Vapor for Facile Fabrication of Silicon Nanostructures

Abstract

Inspired by metal corrosion in air, we demonstrate that metal-catalyzed electroless etching (MCEE) of silicon can be performed simply in aerated HF/H2O vapor for facile fabrication of three-dimensional silicon nanostructures such as silicon nanowires (SiNW) arrays. Compared to MCEE commonly performed in aqueous HF solution, the present pseudo gas phase etching offers exceptional simplicity, flexibility, environmental friendliness, and scalability for the fabrication of three-dimensional silicon nanostructures with considerable depths because of replacement of harsh oxidants such as H2O2 and AgNO3 by environmental-green and ubiquitous oxygen in air, minimum water consumption, and full utilization of HF.

Ultrasmall and phase-pure W2C nanoparticles for efficient electrocatalytic and photoelectrochemical hydrogen evolution

“…We integrated W 2 C/MWNT with p-type Si nanowires and studied their performance for photoelectrochemical (PEC) hydrogen evolution. P-type Si nanowires having an average length of 500 nm were prepared from the Ag-assisted etching of Si wafer (see details in Methods) 42 43 . W 2 C/MWNT was directly dropcast onto these nanowires.…”

In Situ Scanning Electron Microscopy Observation of Growth Kinetics and Catalyst Splitting in Vapor–Liquid–Solid Growth of Nanowires

“…1D semiconductor nanowires have been widely studied for over two decades for their novel physical and chemical properties and a vast range of potential applications in electronics, piezoelectrics, photovoltaics, mechanics, and sensors . With numerous research efforts devoted, tremendous progress has been made in the controlled synthesis of 1D semiconductor nanowires, including the control of diameter, length, composition, structure and orientation . Among all methodologies developed so far, the vapor–liquid–solid (VLS) process, first proposed by Wagner and Ellis for large whisker growth, has emerged as the most successful and widely adopted method for growing 1D semiconductor nanowires due to its great flexibility and high controllability.…”

Metal assisted chemical etching of silicon in the gas phase: a nanofabrication platform for X-ray optics

“…In 2014, two independent papers 8,9 demonstrated that a MacEtch reaction could occur by evaporating and condensing the electrolyte on the surface of a metal patterned silicon. Hu et al 8 demonstrated that the MacEtch reaction occurs at room temperature in the presence of aerated HF in a similar fashion of metal corrosion by air.…”

“…In 2014, two independent papers 8,9 demonstrated that a MacEtch reaction could occur by evaporating and condensing the electrolyte on the surface of a metal patterned silicon. Hu et al 8 demonstrated that the MacEtch reaction occurs at room temperature in the presence of aerated HF in a similar fashion of metal corrosion by air. The oxygen diffusion through the condensed HF/water layer limits the etching rate and the maximum etched depth, so a maximum depth of 6 mm was etched in 3 h. According to Hildreth et al, 9 the electrolyte is evaporated from a liquid solution containing HF and H 2 O 2 and forms a condensed thin layer where the MacEtch reaction occurs.…”