Reverse-biased Diodes

Most recent answer: 10/03/2017

Q:
In a diode that is experiencing reverse bias, the depletion region will increase. When this happens, why aren't the electrons in the negative ions attracted to the positive ions and hence create electron flow from the p-node to the n-node?
- Mike jones (age 16)
San diego
A:

The electrons on the negatively charged ions are bound, in the sense that there's a non-zero amount of energy required for them to break loose. A small reverse bias doesn't provide enough energy for that to happen. The key underlying idea is that these electrons localized on atoms have energies that depend not just on the overall electric field but also on the detailed states available at the individual atom. That's a quantum mechanical effect, with no real classical explanation.

Mike W.


(published on 10/03/2017)