WHY SCR not GCR?

yesterday we were introduced about SCR and after studying it my colleague asked me why its a silicon controlled rectifier why not germanium controlled when both are semconductors. i have no answer but i wish to know the answer does any one has the answer pls reply.

Silicon is cheaper, easier to work, and has some better characteristics than germanium. I think it was silicon that has better temperature characteristics and germanium has lower voltage drops (like germanium diodes) or something like that. NOw that you know what to look for you can probably google to find out more.

http://www.semiconductormuseum.com/Transistors/GE/OralHistories/Gutzwiller/Gutzwiller_Page12.htm
I believe an SCR can be made from germanium but no one makes one. The germanium transistors I used are low voltage and have high leakage. Most SCR applications are relatively high voltage. Leakage will cause the SCR to turn on.

Germanium melts at 947 degree C, silicon melts at 1400 degree's, carbon about 4000. Long before then it will start to diffuse with it's neighbooring materials destroying/altering it's semi-conductor abilities. Maybe one day we'll have carbon semi conductors =) Some recent advances in vapor deposition of carbon has lead to diamond semi conductors, which blow silicon out of the water. Dopeing and mass production are a bit of an issue right now of course.

ronsimpson said:

The germanium transistors I used are low voltage and have high leakage.

Click to expand...

Hey, out of interest, do they still make those? I was trying to look them up a few months ago (vaguely interested in the low VBE), but didn't get very far.

From what little I could find, I got the overall impression they no longer did (like because they were too failure-prone or such?), and that you could only really get them from very old circuits, or from surplus companies who did likewise. Is that the case?

As has already been mentioned, Germanium devices are fairly leaky, this would permanently trigger a thyristor (got over the SCR/GCR thing!) making it completely unusable - plus it would be too low a voltage and current as well.