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New for February 2006!
In 1958 Leo
Esaki, a Japanese scientist and Nobel Prize winner, discovered
the tunnel diode phenomenon (when he wasn't saying "rook,
Godzirra!). If a semiconductor junction diode is heavily doped
with impurities, its I-V curve will have a region of negative resistance
(the slope is negative, or downward). Such diodes are called "tunnel
diodes", and have broad applications in microwaves. This region
has been exploited to create oscillators, but it also makes a very
efficient detector. Why the word "tunnel"? We'd have to
resort to quantum physics to explain that, but we won't, because
no real microwave engineer cares!