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So I'm confused about electrons holes and how they differ from free electrons. I have this question in my mind for months and I couldn't any solid answer.

Qmechanic
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Kamran Sani
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1 Answers1

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In a solid (semiconductor), an electron hole is the absence of an electron where one is expected. In this sense you can think of an electron hole as if it were an air bubble (the absence of water) in a body of water- a local spot where there should be water but there isn't.

In the case of water in the presence of gravity, water falls down- but bubbles in the water fall up instead. For an electron hole, an electric field that would accelerate an electron in one direction will accelerate a hole in the opposite direction- leading one to conclude that in an electron sea, a hole where there is no electron behaves as if it had a positive charge.

niels nielsen
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  • Thank you very much. it helped me understand. – Kamran Sani Apr 13 '21 at 05:49
  • It isnt quite that simple. If it was you couldnt tell electrons and holes apart with the Hall effect. This answer doesnt address why we care about holes at all. If its all just electrons, why even talk about holes? This is a critical part of answering how electrons and holes differ. – Matt Apr 13 '21 at 12:17
  • @matt, you are free to provide your own answer to this question. – niels nielsen Apr 13 '21 at 15:34
  • @nielsnielsen Im considering it, but I dont know if my understanding is good enough to write a good answer. I just often see people get very confused because they keep trying to see holes as "just" missing electrons, instead of treating electrons and holes as equals. In fact, "an electric field that would accelerate an electron in one direction will accelerate a hole in the opposite direction" isnt accurate if we are talking about within a band. At least it disagrees with Ashcroft and Mermin's description based on the semiclassical model. – Matt Apr 13 '21 at 16:33