Hello!
Could someone explain electron holes to me like I’m five? Are they a concrete positive charge, or a mere absence of an electron? I have a lot of question marks in my head regarding this concept. I would appreciate resources that help to understand it too.
Thank you!
Tldr: what’s an electron hole?
In: Chemistry
Holes are an absence of an electron.
I’m not sure how simple I can make it, but here’s a try.
To conduct electricity, electrons have to be able to move freely.
You might be familiar with the concept that electrons sit on specific energy levels and cannot share them. This means every electron has a place. The only electrons that can participate in anything, chemistry or conduction, are only the very outermost ones, called Valence electrons.
When you have enough atoms in a material, you can start sort of mushing everything together and stop thinking about individual atoms. So now imagine that all these valence electrons more like balls on a shelf.
Now, in conductors like most metals, these electrons are already free to move. That’s just how metals work. So they just slide around their shelf freely. Call that the conduction band
But in other materials, they’re still sitting in their designated spaces. Think of it as having a cup they go into on their shelf. Call that the valence band. They can move from cup to cup, but only if there’s an empty one next to them.
Now, above the valence band you’ll still have the shelf of the condition band. If given a kick, an electron can moved from its cup onto it and go ahead and slide around freely, conduct. Semi-conductors are materials where that gap between shelves is small enough to actually be practical to use.
Now, you moved the electron from the cup. You have an empty cup. It’s an absence of an electron, not a real thing. If you zoom in, you see that it’s just electrons moving around.
But when you zoom out, something interesting happens. It starts to seem like the hole is moving about the shelf, sort of like the electrons on the shelf above it. Like some sort of a actual particle. And you can even describe that behaviour with exactly the same math as you do for the electrons. When you do that, you have to give it positive charge, because compared to it’s surrounding it’s more positive by exactly one electron charge.
So while it doesn’t really exist, the way a hole left behind by an electron behaves and the properties it has make it very useful to pretend it’s a “thing”.
Latest Answers