Why Is Silicon Used in Electronic Components?

What you will learn

• State the properties that make a semiconductor suitable for electronics.
• Explain the path from sand to usable silicon crystal.
• Compare silicon with other semiconductor materials and recognise its limits.

Before you start

This article reads best after the one on semiconductors, but each term is explained as it appears.

What does electronics need from a semiconductor?

Electronics needs a material whose conduction we can control. A semiconductor provides it. The “semi” means its electrical conductivity is less than that of a metal but more than that of an insulator.

Most semiconductors are made of crystals, typically silicon. Common conducting elements have a single electron in their outermost shell, while semiconductors have four. This, with other factors, makes silicon crystal suited to controlling current.

Control comes from doping: deliberately introducing impurity atoms into the crystal to change its electrical properties, making the material more or less conductive. Silicon allows this adjustment, so components made from it can be switched on or off as the designer intends.

Why is silicon easy to obtain and cheap?

Silicon is an abundant element found in sand, so the raw material is inexpensive. Sand cannot be used as it is, though. Silicon has to go through a chemical refining process before it becomes crystalline silicon that conducts electricity.

This matters for comparison. A material that is electrically excellent but scarce or expensive is hard to use at scale. For silicon, a common raw material found in sand helps keep the cost low.

How do crystal, wafer and product connect?

Crystalline silicon is cut into thin sheets called wafers. Silicon wafers are the most common wafers for making integrated circuits. The same principle is used for solar panels: blocks of crystalline silicon are cut into very thin wafers and processed into photovoltaic cells.

So one material serves two kinds of product. About 95% of solar panels on the market use either monocrystalline or polycrystalline silicon. Silicon is also the main semiconductor in most electronics.

Silicon is not the only choice. Wafers can also be made from gallium arsenide, silicon carbide or germanium. Radio-frequency chips combine gallium arsenide, gallium nitride and silicon to work at higher frequencies. Silicon solar cells have a theoretical maximum efficiency of about 32%, a trade-off of the material.

Real-world example

Compare a rooftop solar panel with the chip in a phone. Both start from sand refined into silicon crystal. Both use wafers cut thin from the crystal.

The difference lies in the processing that follows. A solar wafer is processed into a photovoltaic cell, while a chip wafer has circuits formed on it. One material, two uses, thanks to different processing.

Common misunderstandings

Silicon is not sand. Sand contains silicon, but it needs chemical refining before it becomes crystal that can conduct.

Silicon is not the only semiconductor. Germanium, gallium arsenide, gallium nitride and silicon carbide are also used, depending on purpose.

A wafer is a form of the material, not yet a product. The same kind of wafer can become a chip or a solar cell.

Frequently asked questions

Is silicon really found in sand?

Yes. Silicon occurs in sand, but it needs chemical refining before it becomes usable crystalline silicon.

Why do chips use silicon wafers?

Silicon wafers are the most common. Silicon is a typical semiconductor whose electrical properties can be adjusted by doping.

Does silicon have limits?

Yes. For solar cells, the theoretical maximum efficiency of a silicon cell is about 32%. Some radio-frequency circuits also need gallium arsenide or gallium nitride.

Summary

• Silicon is a semiconductor whose conduction can be adjusted by doping.
• It is abundant in sand but must be refined into crystal.
• Silicon wafers serve both chips and solar panels, although other materials suit particular needs.