Does anybody know anything Germanium based JFETs, i.e. are/were they ever manufactured commercially, why they seem to be so rare, etc.? I have been searching around and am finding very little information. I saw several research papers on Ge-MOSFETs and SiGe Tunneling FETs, but very little on Ge-JFETs aside from one patent, taken out by TLC Precision Wafer Technologies , and a research paper in Solid State Electronics, both of which have to with Ge-JFETs for use at cryogenic temperatures. The patent is from 1998, but I can't find any info about it on TLC's website (seems like it hasn't been updated in ages). It describes the Ge-JFET as being used for detectors at cryogenic temperatures:

"An object of the present invention is a provide a Germanium junction field effect transistor (Ge-JFET) suitable for use in low noise cryogenically cooled detectors operating at temperatures of in the range of 2° to 4° Kelvin for low audio frequencies in the range of 10 to 100 Hz."

I'm particularly interested in the fact that they are using it for audio; I wonder how a Ge-JFET would do in other audio situations? All the input impedance of a typical JFET with the soft clip of a Ge diode? That sounds like a match made in heaven for guitar effects.

If anybody has more information about all of this, I would love to hear it.

Thanks,
-Carl

 

Does anybody know anything Germanium based JFETs, i.e. are/were they ever manufactured commercially, why they seem to be so rare, etc.? I have been searching around and am finding very little information. I saw several research papers on Ge-MOSFETs and SiGe Tunneling FETs, but very little on Ge-JFETs aside from one patent, taken out by TLC Precision Wafer Technologies , and a research paper in Solid State Electronics, both of which have to with Ge-JFETs for use at cryogenic temperatures. The patent is from 1998, but I can't find any info about it on TLC's website (seems like it hasn't been updated in ages). It describes the Ge-JFET as being used for detectors at cryogenic temperatures:

"An object of the present invention is a provide a Germanium junction field effect transistor (Ge-JFET) suitable for use in low noise cryogenically cooled detectors operating at temperatures of in the range of 2° to 4° Kelvin for low audio frequencies in the range of 10 to 100 Hz."

I'm particularly interested in the fact that they are using it for audio; I wonder how a Ge-JFET would do in other audio situations? All the input impedance of a typical JFET with the soft clip of a Ge diode? That sounds like a match made in heaven for guitar effects.

If anybody has more information about all of this, I would love to hear it.

Thanks,
-Carl

Never heard of them, but that doesn't mean it never happened. You might find more info searching the acronyms; HEMT & MESFET.

 

Never heard of them, but that doesn't mean it never happened. You might find more info searching the acronyms; HEMT & MESFET.

Thanks Ian. Checking those things out now.

 

See

 

See