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Re: Temperature behaviour of semiconductors

Hi William,

Here is a recent EE Times article that can help
on the silicon vs germanium issue:


 From the article: "In the past, the main problem with germanium,
besides its limited availability and high cost, was the impossibility
of growing a stable oxide on it that could passivate the surface,
act as an etch protector and, most important, be used as a high-quality
gate insulator. Silicon, on the other hand, gained from the ability to
grow silicon dioxide, a material with properties precisely matched
to the needs of the semiconductor industry"


There were many cold-cathode tubes developed over the years

voltage regulators (OA2)
rectifiers (0Z4)
Triode switch tubes (ER-21A)
Tetrode switch tubes (KN-22)
Photo-detectors (922)
Photo-multipliers (931A)
waveguide TR and anti-TR switches (721A)
Decade counter tubes for digital computers (TR-DC-11)
Nixie display tubes (NL-5441A)
Radiation detectors (Geiger-Mueller) (MX-168)

And probably more but this is all I could think of
off the top of my head.

It is possible to use the negative resistance characteristic
of an OA2 or even a neon lamp to make an oscillator. I
imagine some type of low frequency amplifier could be
made as well but I don't recall one.

The old arc transmitters of 1914 vintage by Federal
used a big negative resistance "tube" to make a megawatt
(yes megawatt!) level CW/FSK transmitter but they were
heated with kerosene so not exactly cold-cathode but
they didn't have a "heater" or a "filament."

The gas plasma display tubes that are becoming popular
in big TVs these days use unheated cathodes.

So, there are lots of uses for cold-cathode tubes and many
are still in use and even readily available. No L-band
amplifiers  that I know of however!


Tony AA2TX

At 09:25 PM 9/13/2003 +0200, William Leijenaar wrote:

>Its already a while ago I did some tests on "normal" components with 200C 
>temperature and see if I could find any electrical changings afterwards.
>I am still looking for data about the behaviour of electronical components 
>under extreem temp. comditions. I remember that I red some physics book 
>for about 2 years what explained the physical changings of a PN barier 
>with increasing temperature, and also why silicon is used instead of 
>Germanium etc etc... but I can't find it anymore. I can't find any usefull 
>information about this topic at all.
>Somebody knows any source (book, webpage, etc etc) where I can find data 
>about this topic ?????
>Other data from semiconductor behaviour under influenses of forces like 
>radiation, pressure, static energy etc etc is also welcome...
>Besides semiconductors I also have some tube question :o)
>Do unheated tube amplifiers exist ??  (E.g triode with cold cathode)
>Maybe they survive better than silicon components under extreme conditions 
>(radiation, heat/cold)
>(Cold cathode would save power)
>73 de PE1RAH, William
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