>** See ABSE for pics of a silicon NPN transistor chip emitting light.
>
>No trickery involved.
>
>The type is a 2N3439 ( high voltage NPN in TO5 pack)
I believe that's quite plausible.
Some years ago, Bob Pease noted a somewhat paradoxical phenomenon
involving silicon transistors. If you forward-bias one of the two
junctions (either BE or BC, I forget which) and generate a few mA of
current flow, and then read the voltage across the other junction,
you'll measure a nonzero voltage. Where does this come from?
According to Pease, it occurs because the forward-biased junction is
acting as an LED, and the junction you're measuring is picking up the
photons and acting as a photodiode.
I believe that almost all of the light emitted is in the infrared, as
a consequence of the low bandgap voltage of silicon. Possibly this is
changed by the doping characteristic of the silicon in question?
--
Dave Platt <dplatt@[EMAIL PROTECTED]
> AE6EO
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