. They are grown on a silicon substrate and elongated along one direction of the nanostructure diameter from 50 nm to 200 nm and lengths from tens of nanometers to 100 microns, spaced at 100-500 nm. Such yarns can be obtained by etching metal-stimulated – chemical etching of a silicon wafer using metal nanoparticles as initiators. In addition to silicon – a material familiar to the electronics industry, an interesting feature is the ability to kremnievyeh nanowires with time to completely dissolve in the body, causes the interest of specialists in Biomedicine .
Specialists of the Physics Department of Moscow State University University has developed a new method of producing silicon nanowires. It differs from the previously known fact that instead of poisonous hydrofluoric acid (HF) is used to etch a safer and more environmentally friendly ammonium fluoride (NH4F).
The optical properties of silicon nanowires fabricated using the new method, the researchers came to the conclusion that they are superior nanowires obtained by the standard method. In particular, there is a strong localization of light scattering, and in a wide range, thereby achieving extremely low total reflection of light (a few percent) in the ultraviolet and visible regions of the spectrum. In addition, an increase in the interband photoluminescence intensity of silicon (1.12 eV) and Raman scattering in comparison with the original substrates of crystalline silicon. Finally, the new efficient photoluminescence characterized nanowires in the range 500-1100 nm. All this, according to the researchers, expanding the scope of the silicon nanostructures. For example, they can be used in an antireflection coating to improve the efficiency of solar batteries, optical sensors sensitive elements of different substances, photonics and biomedicine.
Source: State University