Silicon is an element of the earth's crust that is second only to oxygen. Silica (also known as silica) is a class of silicate minerals, which are also the main components of sand, quartzite and granite. Although about 75% of the earth is composed of silica, silicon is rare in nature. It was not known until the 19th century. In fact, impure amorphous silicon may have been obtained by Gay-Lussac and Thenard in the first place in 1811 by heating potassium and silicon tetrafluoride. However, when it comes to silicon, people still attribute their findings to Berzelius because it is him. In 1824, the silicon obtained by the above method was further rinsed and purified to obtain pure silicon. It is now possible to use an electric furnace to heat a mixture of silica and carbon to a temperature far above the melting point of silicon (1,414 °C) (1,900-2,350 °C) to achieve large-scale production of silicon.


Silicon Valley: Laser-irradiated silicon surface scanning electron microscopy images (inset) are very similar to the corner of Bryce Canyon National Park in Utah, USA.
According to the US Geological Survey, as of 2007, the world's pure silicon storage including synthetic silicon has exceeded 500,000 tons, which is enough to show its importance to today's technology. More than 90% of the silicon is used to make silicon-containing chemicals and alloys. For example, it is commonly used in the automotive industry for aluminum alloys, as well as silicone greases (characterized to contain silicon-oxygen bonds and silicon-carbon bonds) that are widely used as lubricants, resins, rubbers or sealants. Silica, which is in the form of sand, is the basis for the most commonly used materials, glass and concrete. Aerogels, which are 90% of their volume occupied by pores, are extremely light silica and therefore very effective insulating materials.


While these applications are important, the most profound impact of silicon on today's technology and lifestyle is due to a small fraction (about 5%) of its overall reserves, including computer chips, power transistors, solar cells, and High-purity silicon in various electronic devices such as liquid crystal displays and semiconductor detectors. The miniaturization of silicon integrated circuits has also made great progress in microelectronics, and this field is further advancing toward nanoelectronics. In addition, porous silicon has also contributed to the development of a series of sensors due to its luminescent properties and large surface area. The preparation process of high-purity silicon required for microelectronic devices is cumbersome, usually involves the conversion of crude metal silicon to chlorosilane (a compound containing a silicon-chloride bond), which is reduced and purified by hydrogen into polysilicon after separation and purification. Wafer (smooth thin disk).


The variety of silicon chemistry is amazing, and new discoveries are still emerging in this area. Although the surface area of 1 gram of sand is very small, the same quality, silica particles with nanometer (about 3 nm) pores can easily exceed 1000 square meters (about the surface area of an Olympic swimming pool). The particles with ordered nanoporosity are synthesized in the presence of a surfactant template. This synthetic strategy provides unlimited possibilities for the development of nanomaterials. For example, nanoporous silica particles can be used for catalysis, separation, and environmental cleaning. , drug release and nanotechnology and other fields.


When it comes to silica gel, you have to talk about silicon oxide materials with nanometer precision that are produced on a large scale by various marine organisms. An understanding of the “biosilicide” in nature will provide unlimited potential for environmentally friendly synthesis of new silicon-based materials, and will ultimately lead to biosensors, biocatalysis, and biomolecules now known as “silicon biotechnology”. The development of engineering.


Another striking and technologically promising discovery reflects the importance of revealing the micro-nano structure. In 1998, the Mazur team at Harvard University reported that using a femtosecond laser pulse to illuminate a silicon wafer in the presence of a sulfur-containing gas would make its smooth surface a peaky forest, with the Bryce Canyon National Park in Utah, USA. Similar (pictured). Typically, the silicon surface reflects most of the light, but "black silicon" greatly enhances the visible absorption properties by capturing visible light between the peaks, making it more promising for use in solar cells. Black silicon can also absorb infrared radiation with a wavelength of 2500 nm. Therefore, the new application of black silicon in photovoltaics is also worth looking forward to. This example shows that although silicon has been discovered for 200 years, it still marvels us. n