UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
Why only silicon chip is used in computers? Does it have any special property?
Question Date: 2014-06-11
Answer 1:

Great question! Silicon is an interesting example where material properties are not the only deciding factor for what makes it into consumer products.

Why is Si used in chips for computers?
Silicon is actually not the most optimal electronic material, but it is used instead of other materials with better electronic properties because it is cheap and extremely abundant. In fact, Si is the eighth most abundant element on earth (albeit, you need to do processing beforehand). It's part of what makes all of your electronics affordable, and is often the barrier for other materials to substitute it. But there's a lot of research across the world to discover materials that are comparable or better to silicon. It's an exciting time in electronic materials research!

In general, materials for electronic devices are semiconductors. This is because you want to be able to have a device that can switch between an on and off state at room temperature (otherwise you would need to use your computer in somewhere like a freezer or sauna!). Metals conduct electrons so it would be hard to switch them off, and similarly insulators do not conduct electrons, so turning them on would be equally difficult. Semiconductor materials have properties in that sweet middle spot that's just right. Silicon is an example of such a semiconductor. It is not the best electronic material, but it is good enough.

What makes Si a less than ideal electronic material?
There are most definitely many of reasons for this, such as lower carrier mobilities (e.g. electrons don't move as fast; recall that current is C/s, so slower carriers means you get less current out per second). You can compare it to germanium and gallium arsenide, which have better electronic material properties.

And some extra interesting stuff:
What distinguishes between a metal, semiconductor, and insulator?
The key feature that is often used to differentiate among metals, semiconductors, and insulators is the energy gap. In solid state physics, you find out that electrons in solids live at particular energies called bands. Metals have no gap between bands, which means that electrons can flow between bands and conduct. Semiconductors and insulators have a gap between bands, with the upper chunk of bands called "conduction bands" and lower chunk of bands called "valence bands"; semiconductors have a smaller gaps. This is better understood with a schematic. It turns out that these bands vary in energy as you move across these materials in different directions, so that there are energy minima and maxima between the valence and conduction bands. The band gap is often defined as the energy difference between the conduction band minimum (CBM) and valence band maximum (VBM) (also better understood with a picture; the momentum axis is essentially a particular spot and direction in the material). In this schematic, the CBM and VBM are directly between each other; this is called a "direct band gap". But this need not be the case, the CBM and VBM could be located in different spots, in which case the gap is an "indirect band gap."

This is important for Si in solar cells for instance. Silicon has an indirect band gap, which is less efficient than materials with direct band gaps. But because Si is so cheap and abundant, it is still the dominant material used in making solar cells.

This is quite a bit to absorb (and is in fact a condensed version of many physics and materials science classes), but if this peaks your interest, I'd recommend looking into materials science for future study!

Hope this helps!

Answer 2:

A computer chip needs to be built out of a semiconducting material, and most of these chips are indeed built with silicon even though there are other possible materials.

The most important reason for why silicon is the most popular material for computer chips is that billions of dollars and incredible amounts of time have been invested over the past several decades perfecting the process of making very reliable, ever smaller transistors with millions and sometimes billions of working transistors per chip. So even if another material might be better than silicon, a huge amount of time (many years!) and money (billions of dollars!) would still be needed to perfect the designs and manufacturing process.

The first transistor was created in 1947 at Bell Labs and was made with Germanium, another semionducting material. The first silicon transistor was created in the 1950's. Transistors can also be made from many other materials.

One reason for why silicon was chosen over germanium is that silicon operates better at high temperatures because the bonds with the electrons are stronger in silicon than in germanium. Germanium has weaker bonds to its electrons and at high temperatures these bonds may be broken and lead to worse performance.

Another reason why silicon became dominant is that it is very easy to create a high quality thin insulator on the surface of a silicon chip, because you can just put silicon in a hot furnace with oxygen and it will form a thin film of silicon dioxide which performs as an excellent insulator which gave it a huge advantage when MOSFETs were first created. Modern computer chips are formed entirely with insulated gate MOSFET devices, this insulator is used to reduce power consumption and increase performance.

Some applications today such as very high-speed high-power transistors for wireless applications including communication and radar use other more specialized semiconductors including Gallium Nitride (GaN) because electrons move very quickly in GaN and the electron bonds are very tight in GaN so it can be operated up to higher voltages. Ultra-high-speed transistors operating at up to 1000GHz are built with Indium Gallium Arsenide semiconductors because electrons move even faster in this material so it is very difficult for silicon transistors to match the speed, these transistors may be used someday for ultra-high-speed wireless communication links with far more bandwidth than is possible today.

It is becoming more and more difficult and expensive to design the next generation of silicon transistor because engineers are starting to run up to the limits of the material's capabilities. However engineers have always found ways to keep improving silicon devices even when it seemed impossible, so nobody is sure for how long these transistors will keep improving. Maybe someday another material will take over from Silicon which has been dominant for decades.

Answer 3:

This is a great question! Silicon is an essential component of modern electronics because it is an element with very special properties. Namely, silicon in the pure form is a semiconductor, which means it possess properties of both a metal (which conducts electricity) and an insulator (which blocks electricity). By controlling semiconducting silicon, we can manipulate electrical signals that ultimately are the building blocks of transistors, memory chips, computer processors, and all of electronics! Silicon is also a relative abundant element on Earth, though in nature silicon is often combined with other molecules such as oxygen (i.e. silica or sand) so man-made processing is needed to purify silicon. However, there are other materials that are commonly also used in the electronics industry, such as germanium, gold, copper, aluminum, magnesium, nickel, cadmium, and so on.

Answer 4:

Yes, silicon has many special properties that make it ideal for using in computer chips. Silicon has both "scientific" and "technological" advantages over many other materials. Scientific advantages are what make Si actually work for the purpose that we want and technological advantages are what make it cheap and scalable to big production facilities.

Scientifically, Si is a semiconductor material, which means that it's somewhere in between a strict electrical insulator like glass and a strict metal like copper. One of the most useful aspects of semiconductors is that their level of conductivity can be changed by using "dopants", which are small concentrations of impurity atoms.

On the technological side, silicon can also be made unbelievably pure at amazingly large size scales. Enormous silicon boules as tall as the floor to the ceiling are perfect crystals with vanishingly small numbers of defects. This is why adding in impurities can be such a precise process, and allow engineers so much control.

The only material that can be made purer than silicon is germanium. There was a time when it was unclear if Si or Ge would become the platform for computer chips, but Si won out for a couple more scientific and technological reasons: Si is able to grow a stable, insulating oxide (SiO2) when heated very hot in a furnace. This is very useful for making devices like transistors, which require insulating regions. Secondly, Si is dead cheap! It's the most common element in the Earth's crust and is basically isolated from sand.

So in short, silicon is a highly pure, easy to use, and cheap semiconductor, perfect for the now huge computer chip industry.

Answer 5:

Silicon is used because it can be used as either an insulator (doesn't allow electricity to flow) or a semiconductor (allows a little flow of electricity). This is important for making chips. Also, it is very, very cheap.

Answer 6:

Yes; silicon is a semiconductor, which allows it to control the flow of electricity closely between the components of the chip. I am not enough of an electrician to explain how this works in detail, though.

Answer 7:

This is a good question. First, let's remind ourselves of what computer chips are. Computer chips are small plates of semiconducting material, such as silicon, which have a set of electronic circuits that can be used to transmit data. Being able to manipulate the voltages across these electronic circuits is important for controlling the efficiency of data transfer. Silicon is a good material for this because it is relatively easy to manipulate the conductive properties of silicon by "doping" it with other elements. While silicon is not the only semiconductor material out there, it is certainly much cheaper to create circuits with silicon as compared with other semiconductors. I hope that helps!

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use