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I was reading a question and found this interesting answer.

https://physics.stackexchange.com/a/334378/113093

Which mentions these materials that aren't very conductive, that are used in every day computers (silicon/germanium). I am also curious if the semiconductor material that is chosen is needed for higher conductivity, i.e., using Germanium over silicon.

I am curious why Gold is such a prevalent item (or was) in chip making, when they could have used cheaper and better conducting materials like silver/copper.

Am I missing something why gold was used over these other materials?

Thanks.

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closed as off-topic by The Photon, Yashas, Kyle Kanos, John Rennie, Jon Custer May 22 '17 at 13:33

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    $\begingroup$ Gold is only used for contacts because, unlike silver and copper, gold's surface doesn't oxidize. Gold is very expensive, so it is only used when necessary. As for semiconductor materials, it's not so much a matter of which material (Si or Ge) has better electrical conductivity. For speed, it's more a matter of the carrier mobilities and I believe that Ge has higher carrier mobility than Si does. $\endgroup$ – Samuel Weir May 21 '17 at 18:58
  • $\begingroup$ Ah, oxidation, I forgot about that... I've seen some copper in chips get really really nasty. So gold stays pure then? I know it's expensive, which is why I was curious why the others weren't used more often. Gold used to be used much much more in the past, but these days there probably isn't much if any gold used in chips. What are "Carrier mobilities?" Your post seems like a good answer instead of a comment. $\endgroup$ – XaolingBao May 21 '17 at 19:04
  • $\begingroup$ @SamuelWeir Put your comment in an answer, so that it can be accepted....... $\endgroup$ – Wrichik Basu May 21 '17 at 20:19
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    $\begingroup$ I do not know the reason as to why this question was put on hold. Platinum or rather alloys containing platinum are used (e.g. contact breaker points) because it is harder than gold and less susceptible to wear in application where contact is made repeatedly and often. There is also a cost evaluation during the design phase. $\endgroup$ – Farcher May 22 '17 at 22:35
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    $\begingroup$ The reason is that gold is almost as good as conductor as silver and copper and it stays unblemished in the normal environment. Silver is getting black in air (silver sulphide from the sulphur dioxide air pollution) and copper builds a patina which is less conductive. The most important reason is its extreme malleability: The gold you see is most likely only a very thin film on less noble metals and is therefore quite cheap because it is only a very small amount of material. $\endgroup$ – Thorsten S. May 23 '17 at 21:04