Billel Salhi

CMOS compatible strategy based on selective atomic layer deposition of a hard mask for transferring block copolymer lithography patterns

A generic, CMOS compatible strategy for transferring a block copolymer template to a semiconductor substrate is demonstrated. An aluminum oxide (Al(2)O(3)) hard mask is selectively deposited by atomic layer deposition in an organized array of holes obtained in a PS matrix via PS-b-PMMA self-assembly. The Al(2)O(3) nanodots act as a highly resistant mask to plasma etching, and are used to pattern high aspect ratio (>10) silicon nanowires and nanopillars.

The collagen assisted self-assembly of silicon nanowires

The paper reports on self-assembly of silicon nanowire junctions assisted by protocollagen, a low cost soluble long fiber protein and precursor of collagen fibrils. First, the collagen was combed on an octadecyl-terminated silicon surface with gold electrodes. Then the combed surface was exposed to an aqueous suspension of silicon nanowires. In order to increase electrostatic interactions between the positively charged collagen and the nanowires, the nanowires were chemically modified with negatively charged sulfonate groups. The interaction of collagen with the sulfonated nanowires, which mimics the native collagen/heparin sulfate interaction, induced self-assembly of the nanowires localized between gold electrodes. The proof of concept for the formation of spontaneous electrode-nanowire-electrode junctions using collagen as a template was supported by current-voltage measurements.

Bulk micromachining of silicon using electron-beam-induced carbonaceous nanomasking

This paper reports on an alternative nanolithographic technique for bulk micromachining of silicon. We show how to selectively etch Si(110) in aqueous KOH solutions using electron-beam-induced nanomasking. Already nanometre thin carbonaceous films can completely suppress the wet anisotropic chemical etching of Si performed in alkaline solution (10?wt% KOH+5?wt% isopropanol). It is shown that under optimized conditions, this approach can be exploited for the fabrication of three-dimensional micro-?and nanostructures.

Synthesis and Optical Properties of Silicon Oxide Nanowires

The paper reports on the synthesis and structural characterization of amorphous silicon oxide nanowires (SiONWs). The nanowires were prepared using the solid-liquid-solid (SLS) technique and display an average mean diameter in the range of 20-150 nm and 15-20 μm in length. Energy dispersive spectrometry (EDS) analysis revealed that the nanowires consist of Si and O elements in a ratio of approximately 1:2. The result was corroborated by the presence of a single peak at around 103 eV in the X-ray photoelectron (XPS) spectrum. As-prepared SiONWs display blue photoluminescence (PL) centered ∼ 400 nm. The blue luminescence is inhomogeneous with an increase in the PL peak intensity by a factor of 1.8 at certain areas of the surface. Next, we have investigated the effect of high-pressure water vapor annealing (HWA) on the PL and found that while the PL became homogeneous, a decrease of its intensity by a factor 2 was observed. The origin of the blue emission could be attributed to defect centers of oxygen deficiency in the wires.