Si • Atomic Number 14
Silicon
Silicon is a metalloid belonging to the carbon group. Pure, elemental silicon is gray-black in color and exhibits a typical metallic luster, often with bronze or bluish hues. It is the second most abundant element in the Earth’s crust, surpassed only by oxygen. Similar to water, silicon shows a density anomaly—its liquid form is denser than its solid form.
In nature, pure silicon does not occur because it is too reactive, but it is present in nearly all rocks. The name silicon is derived from the Latin words silex or silicis, meaning “flint.”
Due to its atomic structure, silicon is the most important semiconductor in the electronics and technology sectors.
Silicon is also an essential trace element for the human body, primarily absorbed through plant-based foods, and plays an important role in connective tissue.
China is the leading producer of metallurgical-grade silicon, while Germany, the United States, and Japan are world leaders in the production of high-purity silicon for semiconductors.
Because of its critical role in the production of semiconductor chips, the electronics industry, and solar energy, silicon metal is classified by the European Union as a strategic raw material.
Silicon compounds have played an important role as building materials throughout human history. Due to their sharp edges, silicon-containing rocks were already used as tools in the Stone Age. Obsidian, a particularly suitable material for tools, was mined and traded in prehistoric times.
The production of glass from quartz sand began around 3500 BC in Mesopotamia and Egypt.
As an element, silicon was probably first produced by Antoine Lavoisier in 1787 and independently by Humphry Davyin 1800, though both mistakenly believed it to be a compound.
In 1811, the chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard (cf. Thénard’s blue) obtained impure, amorphous silicon.
The Swedish chemist Jöns Jakob Berzelius was the first to recognize the elemental nature of silicon and gave it its name.
The English term “silicon” was introduced in 1831 by Thomas Thomson, who chose the suffix “-on” to indicate the chemical relationship to carbon.
The first production of pure, crystalline silicon was achieved in 1854 by the French chemist Henri Étienne Sainte-Claire Deville through electrolysis.
At the turn of the 20th century, the first industrial silicon production began, using the reduction of quartz sand with carbon in an electric arc furnace.
In 1916, DuPont started large-scale production of silicon metal for steel alloys.
By the mid-20th century, the demand for high-purity silicon for transistors led to the development of the Siemens process, which involves chemical vapor deposition of silane (SiH₄) and its thermal decomposition to ultra-pure silicon.
This marked the beginning of the silicon age in semiconductor technology.
Silicon is used industrially in various forms, depending on its purity and chemical structure.
Silicon dioxide, i.e. quartz sand, is the basic material for glass.
Ferrosilicon is widely used in iron metallurgy. It is a master alloy for the production of steel and cast iron, as well as a precursor for the production of high-purity silicon for the photovoltaic and semiconductor markets. Ferrosilicon is also used as a reducing agent for the extraction of metals.
Metallurgical silicon, which is extracted from quartz sand, is used in aluminum alloys in lightweight construction (automotive industry). About half of the silicon metal produced goes to this sector.
Silicon metal is used to produce high-purity polysilicon with a purity of over 99 percent (high-purity) and high-purity monocrystalline silicon. Polysilicon is used in solar cells and in the semiconductor industry. Monocrystalline silicon is used in computer chips, processors, and high-performance electronics.
Important silicate minerals include clays, feldspars, olivine, pyroxenes, amphiboles, micas, and zeolites.
For silicon extraction, quartz sand is particularly suitable. As silicon is the second most abundant element in the Earth’s crust, it is widely distributed.
Metallurgical-grade silicon with a purity of 98 to 99 percent is produced by reducing quartz sand with carbon in electric arc furnaces.
High-purity silicon is obtained from metallurgical-grade silicon via the Siemens process or in a fluidized bed reactor.
The production of silicon metal is extremely energy-intensive. China dominates the global market, accounting for 70 to 80 percent of total output, with major producers such as Hoshine Silicon and Tongwei.
The annual global production of silicon metal is estimated at around 3.3 to 3.8 million tonnes.
Aluminum, silicon carbide, and silicomanganese can replace ferrosilicon in some applications.
Gallium arsenide and germanium are the most important substitutes for silicon in semiconductor applications.
Critical and Strategic Metals
