What's the difference between an electron hole and a positron?

[ddd1600]

Qualitatively speaking, an 'electron hole' and a positron sound quite similar. Are they they same? If they are, why are different terms used and what is the utility of that, and if they aren't the same, am I completely wrong in assuming that they are in some way analogous? What kind of tree am I barking up here?

 

[whybother]

A positron is an anti-electron (as in, an antiparticle, as in, an actual particle). An electron hole is just a conceptual thing, to make nice mathematics for solid state physicists. An electron hole is just the lack of an electron, not an antiparticle... or a particle at all.

 

[whybother]

Actually the wikipedia on electron holes addresses that exact question too : http://en.wikipedia.org/wiki/Electron_hole

 

[ddd1600]

Seeing that electron holes "flow" in the opposite direction of the electron current in a wire, its basically just a "flowing" of the absence of electrons? What is the point of even creating an abstraction to explain something like that? I know this is how it goes in physics, but why on Earth would one want to articulate the "flow" of an absence?

Is it the flow of positive charge? And if it is, what contains that charge? Don't you need some type of substance to carry that charge? (this is where I was going with the positron bit)

(I think I'm going to like this forum...:)

 

[whybother]

It's not the flow of charge, it's really the not-flow of charge.

When an electron leaves a state a for state b, we can talk about the electron traveling from a->b. Or, we can also talk about "the hole" traveling from b->a . The hole really isn't anything... The hole is just a place that doesn't have an electron, but 'should'. The wiki article I linked has a really nice analogy for hole conduction you should read under the first section.

 

[ddd1600]

Oh, so the positive charge would be a field-type existence which originates in the protons of the conducting metal or metalloid?

 

[whybother]

Oh, so the positive charge would be a field-type existence which originates in the protons of the conducting metal or metalloid?

That's certainly not the wording I would use, hah, but it's in a sense the right idea.

When you take an electron away from a neutral atom, it becomes positive, because of the proton, same for any neutral structure. Metals and Metalloids, when we are talking about bandgap structure, become much more complicated, but the basic idea is the same. The 'hole' though really isn't positively charged, but mathematically, it's 'the opposite' of an electron (but not in the same sense that a positron is).

 

[ddd1600]

Indeed, that's more than good enough for government work, thanks.

 

[Bob S]

Positrons annihilate with electrons in a few nanoseconds, emitting two 0.511 MeV gamma rays.