Influence of the doping level on the porosity of silicon nanowires prepared by metal-assisted chemical etching.

A systematic method to control the porosity of silicon nanowires is presented. This method is based on metal-assisted chemical etching (MACE) and takes advantage of an HF/H2O2 etching solution and a silver catalyst in the form of a thin patterned film deposited on a doped silicon wafer. It is found that the porosity of the etched nanowires can be controlled by the doping level of the wafer.

Ag-mediated charge transport during metal-assisted chemical etching of silicon nanowires.

The charge transport mechanism during metal-assisted chemical etching of Si nanowires with contiguous metal films has been investigated. The experiments give a better insight how the charges and reaction products can penetrate to the etching front. The formation of a layer of porous Si between the metal film and the bulk Si is a prerequisite for the etching process.

Quasi-radial growth of metal tube on si nanowires template.

It is reported in this article that Si nanowires can be employed as a positive template for the controllable electrochemical deposition of noble metal tube. The deposited tube exhibits good crystallinity. Scanning electron microscope and transmission electron microscope characterizations are conducted to reveal the growth process of metal tube, showing that the metal tube grows quasi-radially on the wall of Si nanowire.

Metal-assisted chemical etching of silicon: a review.

This article presents an overview of the essential aspects in the fabrication of silicon and some silicon/germanium nanostructures by metal-assisted chemical etching. First, the basic process and mechanism of metal-assisted chemical etching is introduced. Then, the various influences of the noble metal, the etchant, temperature, illumination, and intrinsic properties of the silicon substrate (e.

Sub-100 nm silicon nanowires by laser interference lithography and metal-assisted etching.

By combining laser interference lithography and metal-assisted etching we were able to produce arrays of silicon nanowires with uniform diameters as small as 65 nm and densities exceeding 2 x 10(7) mm(-2). The wires are single crystalline, vertically aligned, arranged in a square pattern and obey strict periodicity over several cm(2). The applied technique allows for a tailoring of nanowire size and density.

Sub-20 nm Si/Ge superlattice nanowires by metal-assisted etching.

An effective and low-cost method to fabricate hexagonally patterned, vertically aligned Si/Ge superlattice nanowires with diameters below 20 nm is presented. By combining the growth of Si/Ge superlattices by molecular beam epitaxy, prepatterning the substrate by anodic aluminum oxide masks, and finally metal-assisted chemical wet etching, this method generates highly ordered hexagonally patterned nanowires. This technique allows the fabrication of nanowires with a high area density of 10(10) wires/cm(2), including the control of their diameter and length.

Three-beam interference lithography: upgrading a Lloyd's interferometer for single-exposure hexagonal patterning.

Three-beam interference lithography is used to create hole/dot photoresist patterns with hexagonal symmetry. This is achieved by modifying a standard two-beam Lloyd's mirror interferometer into a three-beam interferometer, with the position of the mirrors chosen to guarantee 120 degrees symmetry of exposure. Compared to commonly used three-beam setups, this brings the advantage of simplified alignment, as the position of the mirrors with respect to the substrate is fixed.

Ordered arrays of vertically aligned [110] silicon nanowires by suppressing the crystallographically preferred <100> etching directions.

The metal-assisted etching direction of Si(110) substrates was found to be dependent upon the morphology of the deposited metal catalyst. The etching direction of a Si(110) substrate was found to be one of the two crystallographically preferred 100 directions in the case of isolated metal particles or a small area metal mesh with nanoholes. In contrast, the etching proceeded in the vertical [110] direction, when the lateral size of the catalytic metal mesh was sufficiently large.