|Why only silicon chip is used in computers? Does
it have any special property?|
|Question Date: 2014-06-11|
Great question! Silicon is an interesting example
where material properties are not the only
deciding factor for what makes it into consumer
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
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
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
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
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
Hope this helps!
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
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.
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
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
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.
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.
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,
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!
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