Try 20Amperes, really cool fireworks....

Terry


At 04:28 PM 8/20/99 -0400, you wrote:
>Hi all,
>
>This is actually a follow-up to a thread a while back on strange
>opto-coupling effects in bipolar transistors. IIRC, It was stated that
>reverse-biased transistor junctions will sometimes emit light,by a process
>similar to that which takes place in LEDs.
>
>Since then, I have been trying to improve my knowledge of the theory behind
>semiconductors and the book that I was reading pointed out that LEDs are
>usually made out of GaAs or GaP, not Si or Ge,because Si and (I think) Ge
>are indirect bandgap semiconductors, meaning that electron transistions
>across the bandgap consist not only of energy transactions, but also
>momentum changes. The net effect is that the energy of am electron(or hole)
>falling across the bandgap is given off as light in GaAs and GaP,but as
>vibrational energy to the lattice in Si and Ge.
>
>SO, my question to the gurus here is: how can a normally doped Si or Ge PN
>junction emit light?
>
>Thanks in advance,
>
>Sean
>
>|
>| Sean Breheny
>| Amateur Radio Callsign: KA3YXM
>| Electrical Engineering Student
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