silicon
Silicon (Si) is a metalloid, i.e., an element with properties intermediate between metals and nonmetals. Its atoms are arranged in a diamond-like lattice. It is the second most abundant element in the Earth's crust, found in quartz and silicates. A bandgap of 1.1 eV makes it a classic semiconductor: doping with phosphorus creates free electrons (n-type), and with boron—holes (p-type). The contact of p- and n-regions forms a p–n junction, the basis of diodes, transistors and solar cells.
History
Swedish chemist Jöns Jacob Berzelius first obtained pure silicon in 1824. But its electronic talents were discovered much later. In the 20th century, scientists learned to purify silicon and add impurities (doping), creating the transistor—the digital age began.
How it works
Pure silicon blocks the movement of charges, like a roadblock. A small addition of boron creates vacant spots—'holes', through which current is passed along a chain. The addition of phosphorus, conversely, gives extra electrons. By combining regions with different dopants, we get switches that process information.
💡 The whole Silicon Valley is named after this element. The first silicon transistor was made in 1954, and since then the number of transistors on a chip has been doubling approximately every two years (Moore's law).