Properties Of Silicon Nanowires Research Articles

The effects on the field emission properties of silicon nanowires by different pre-treatment techniques of Ni catalysts layers

Silicon nanowires (SiNWs) were synthesized directly from silicon substrates via a catalytic reaction by thermal CVD system. Ni catalyst layers were deposited on silicon substrates by RF sputtering and electroless-plating pre-treatment techniques, respectively. It was found that the average diameters, lengths, and growth densities of SiNWs by the RF sputtering pre-treatment technique was larger than that by the electroless-plating pre-treatment technique. Furthermore, a better and more stable emission property of the SiNWs was also observed by the RF sputtering pre-treatment technique. Therefore, it was then concluded that the growth mechanism and the emission properties were both strongly influenced by the Ni catalyst layers of different pre-treatment techniques.

Growth of silicon nanowires on H-terminated Si {111} surface templates studied by transmission electron microscopy

We have studied the growth of silicon nanowires (SiNWs) by means of transmission electron microscopy. SiNWs are grown from nanocatalysts via the Vapor-Liquid-Solid (VLS) mechanism using silane (SiH4) gas as a source gas. The nanocatalysts are prepared on a hydrogen (H)-terminated Si surface. We have examined the formation mechanism of nanocatalysts on H-terminated surface and have observed several structural variants of SiNWs. According to the study we have suggested that many structural variations of SiNWs are possible, which modify the structural properties of SiNWs to great extents.

Silicon Nanowires as pH Sensor

Silicon nanowires (SiNWs) have been used as a sensing layer in an extended-gate field-effect transistor (EGFET) for the measurement of solution pH. SiNWs were synthesized directly from silicon substrates via a catalytic reaction in N2 atmosphere at 955°C. The SiNWs have an average diameter of approximately 30–50 nm and a length of up to a few tens of micrometers. Here, silicon bulk materials and SiNWs were used alternately as the sensing layer in an extended-gate field-effect transistor in measuring solution pH. Experimental results showed that the pH sensitivity of silicon bulk materials is poor. However, good pH sensing properties of SiNWs, with a sensitivity of 58.3 mV/pH, was observed. Therefore, it was suggested that the pH sensitivity of silicon bulk materials was greatly improved by downsizing them to the nanoscale.

Surface reactivity of Si nanowires

The chemical reactivity of hydrogen-passivated surface of silicon nanowires (SiNWs) towards the reductive deposition of silver and copper ions from solution is reported. SiNWs synthesized by laser ablation were used in the investigation. The surface properties of SiNWs after the removal of the surface oxide were studied. It is found that the surface silicon of the SiNWs can readily reduce silver (I) and copper (II) ions to metal aggregates of various morphologies on the SiNW surface at room temperature. The reaction products have been characterized with scanning electron microscopy, energy dispersive x-ray spectroscopy, high-resolution transmission electron microscopy, electron energy loss spectroscopy, and x-ray photoelectron spectroscopy. By varying the concentration of Ag(I) ions in the solution, nanostructures of silver with different shapes and sizes can be obtained. This approach for synthesis of metal nanostructures offers a potential method for the preparation of desired metal catalysts.