Why Does Nottingham Heating Occur in Field Emission?

[Benindelft]

Hi,

Can anyone explain exactly why in field emission you get Nottingham heating?

I can understand that you get joule/ resistive heating that makes sense. I can understand that you get cooling, the electron leaves the metal there is a loss of energy.

But why does it matter if it is above or below the Fermi level?

I would have thought that as the electron escapes there is still loss of energy.

next up:
what is then the effect of photo emission / photofield emssion ?


Thanks

Ben

 

[Benindelft]

OK,

I got the answer to my first bit and am pretty sure about the second - but this is an interesting bit of physics so any further discussion would also be fun.

Question was:
Can anyone explain exactly why in field emission you get Nottingham heating?
As I understand it the answer is:
The electron comes from below the Fermi level, it creates a hole which is destroyed by the current flowing. In metal the current carrying electrons have (on average??) the Fermi energy so the net gain in heat energy.

Now for the photon emission (CW)...

The photon excites the electron creating the electron hole pair. If the electron escapes then the hole is replaced by a conduction electron- this results in heating...

Correct?