Re: gEDA-user: LED in reverse

[John Doty <jpd@xxxxxxxxxxxxx>]

On Nov 20, 2006, at 8:33 AM, Karel Kulhavy wrote:

> But the breakdown means that electron go through the diode just the  
> other way.
> Why do the atoms stay the same when hit by electron from one side  
> and something
> permanently changes in them when hit from the other? Are they  
> asymmetric?

They don't necessarily flow in the same place. Breakdown is often at  
surfaces, not in the bulk. It's also often localized, so power  
density can be much larger in breakdown than in forward flow.  
Dissipation mechanisms can differ. Breakdown creates high energy  
("hot") electrons that can drive chemical changes in materials.

If you're driving at 100 km/h and stop your car with the brakes no  
damage results. If you stop by driving into a stone wall, on the  
other hand, the car will be destroyed, and you're not likely to  
emerge in good shape either. Same energy, but different dissipation  
location and mechanism...

John Doty              Noqsi Aerospace, Ltd.
jpd@xxxxxxxxx




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