Solicon: Uses of silicon in electronics and semiconductors

Home	Basics of Electronics	History of Electronics	Electronics Terms	Soldering in Electronics	Electronic Circuits
Electronic PCB Assembly Machines & Tools	Electronic Components	Electronic / Electrical Materials & Consumables	Consumer Electronics	Electronic Companies	PCB (Printed Circuit Board)
Electronics Articles	Electronics News	Electronics Videos	Electronics Images	Electronics Q&A

Electronics >> Basics of Electronics >> Silicon

Silicon, atomic number 14 on the periodic table, is a semiconducting material from which integrated circuits (computer chips of all types--processors, memory chips, etc.; CCDs; transistors; etc.) are created.

Silicon is one of the most common elements on Earth in the Earth's crust, it's second in mass only to oxygen and can be found in any quartz crystal. Beach sand is largely silicon. Silicon is also the semiconductor material out of which almost all modern transistors are made.

Semiconductor devices are made primarily of silicon ("Si"). Pure silicon forms rigid crystals because of its four valence (outermost) electron structure -- one Si atom bonds to four other Si atoms forming a very regularly shaped diamond pattern.

Pure silicon is not a conductor because there are no free electrons; all the electrons are tightly bound to neighboring atoms.

To make silicon conducting, producers combine or "dope" pure silicon with very small amounts of other elements like boron or phosphorus. Phosphorus has five outer valence electrons. When three silicon atoms and one phosphorus atom bind together in the basic silicon crystal cell of four atoms, there is an extra electron and a net negative charge.

This type of material is called n-type silicon. The extra electron in the crystal cell is not strongly attached and can be released by normal thermal energy to carry current; the conductivity depends on the amount of phosphorus added to the silicon.

Boron has only three valance electrons. When three silicon atoms and one boron atom bind with each other there is a "hole" where another electron would be if the boron atom were silicon. This gives the crystal cell a positive net charge (referred to as p-type silicon), and the ability to pick up an electron easily from a neighboring cell.

The resulting migration of electron vacancies or holes acts like a flow of positive charge through the crystal and can support a current. It is sometimes convenient to refer to this current as a flow of positive holes, but in fact the current is really the result of electrons moving in the opposite direction from vacancy to vacancy.

Learn More on Basics of Electronics:
Electronics Definitions	Rules of Electrical Circuits	Wiring Symbols
What is an electronic circuit?	What is charge?	Voltage
Current	Batteries	Resistors
Ohm’s Law	Power	Capacitors
Inductors	Semiconductor devices	Silicon
Diodes