SiGe Microwave Schottky Diodes?

Now why would you want to know that? I would suspect they would use the cheaper and more readily available materials. I believe thats why they quit making Ge transistors . . . Scott

SiGe is cheaper than GaAs because it is built on Si substrate and thus Si fabrication know-how can be applied directly on SiGe. Si is the cheapest while GaAs is the most expensive. (4'' Si-substrate wafer ~ US$10 and 4'' GaAs ~ $340.) However, Si is the slowest and GaAs is the fastest. Therefore, there are both Si and GaAs products targeting different markets.

For SiGe, it is a major contender to GaAs due to its lowcost and pretty good performance (becoming better and better due to the input of research fundings from Si area). It may due to historical reason that it is less common. E.g. First GaAs FET appeared in 1966 while the first SiGe FET was in 1985.

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