Actually i am get confused with electron mobility & it's role in deciding a material for Some particular application.
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What do you know about germanium and silicon? What have you searched for on Google? – Greg d'Eon Apr 09 '15 at 16:14
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What is this "some particular application", specifically? – Nick Alexeev Apr 09 '15 at 16:34
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2You might be interested in this old question: What is silicon germanium? – The Photon Apr 09 '15 at 16:52
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Germanium alone makes for some pretty poor devices. It was the original material used for transistors primarily because it is easier to work with than Silicon.
Mixing Silicon and Germanium in a heterostructure CAN be helpful for high-speed devices because it increases strain in the device. In some cases strain adding in specific ways can speed up switching.
The highest-speed devices use compound semiconductors such as GaAs and InP. They have much higher electron mobility so they can operate at higher speeds. These materials are challenging to work with and have much higher defect density than Silicon so the level of integration is much lower. Typically you see small, fast circuits made with them such as preamps, TIAs, drivers, and registers used for high-speed communications applications. III-V materials are also good at power handling so you see a lot of GaAs power amps in mobile devices.
Keep in mind that as Silicon scales it becomes faster and continually takes over domains that previously was the domain of III-V devices.
crgrace
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Increasingly, GaN is becoming attractive for the switches used in power electronics. This is a domain where making devices smaller and reducing supply voltage isn't an option, and superior physics wins. – Zulu Apr 09 '15 at 21:31