y is silicon only is used for semiconductors y not other
In practical terms silicon has better characteristics than germanium which exhibits large leakage currents in reverse biassed junctions which are very temperature dependant. Gallium is good and exhibits faster mobility enabling faster devices but it is also expensive in production. Basically Silicon is almost an ideal material and can be grown in large pure crystals , can be cut , polished , and although brittle is reasonably strong. Ray.
Only semiconductors can be used as semiconductors.
Silicon is widely used for certain semiconductor applications. Germanium is used in photodiodes, Gallium Arsenide in RF devices, Gallium Nitride is used in Blue LEDs and SiGe is used for making tunnel diodes. InP, AlN, InGaN, AlGaAs are all commonly used semiconductor materials.
The advantage with Silicon (which is why it is used for chip-making, among other reasons) is the ability to grow large defect-free single crystals pretty cheaply. Look up the Czochralski Process.
Silicon is also unbelievably abundant undergroud. It is one of the most abundant elements on earth. Much of the mantle is MgSiO3, so we cannot run out. Probably one of the reasons it is so cheap.
It is worth pointing out that semiconductors are not made from pure silicon, but rather they contain dopants such as phosphorous to form n and p type doped semiconductors which have different properties than pure silicon.
Silicon has not always been the preffered semiconductor of choice in electronics. When semiconductor devices were first developed, Germanium was the semiconductor of choice because silicon could not be grown in sufficiently large quantities with sufficient purity.
We also should not overlook the fact that Si does not have a direct band gap (the maximum of the valence band is not at the same k or momentum value as the minimum of the conduction band). This makes Si not the prefered semiconductor for optical purposes.
Semiconductors other than silicon are used. Silicon has many desirable properties, like a stable native oxide (glass) that can be used for photolithographic purposes.
However, germanium is useful for some applications even today, and Gallium-arsinide and other semiconductors are often used for very high speed devices.
IIRC, silicon is much quicker to fabricate.
There are semiconductor technologies that put germanium islands in silicon and all kinds of other weird things.
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