transistor doping with gold

[senam53]

hi,
if transistor is doped with gold ,,can i call it a digital transistor
or its just analogue used in digital applications...
please if you have a site or sheet or book ,could u give me the link
thx in advance

 

[Jack// ani]

There is no such thing as digital transistor at physical level!!

Real world is analog, and that is how it works.

 

[flatulent]

Back in the days of bipolar transistor logic there was the problem of stored base-emitter and base-collector charge which caused the turnoff to be prolonged. (This was before the days of schottky clamps which kept the transistor from going into saturation.) Gold was introduced in the doping process to put some energy levels in the bad gap which made the stored charge go away faster.

 

[dick_freebird]

Gold was used as a lifetime killer. Usually put in just a tiny
region of the base, because you can't afford to kill the lifetime
in the active base, just want to recombine the stored charge.
I haven't seen this since the 80s in ICs, and even then it was
not real popular with the fab guys (how to keep it off the
tube walls and not have it end up on the next non-gold-doped
boat was a problem; I think they kept special tubes for the
gold doped stuff, which wasn't much of a volume runner).

Other metallic contaminants can have the same effect.