- #1
nonequilibrium
- 1,439
- 2
Hello,
For simplicity's sake, let's take a np junction.
Say we connect the left side (n-pole) to a POSITIVE voltage; this is called a reverse bias, because it will result in a small current from n to p. In other words: electrons will travel from p to n across the junction (and holes will go from n to p, but let's just talk about the electron movement to keep it clear). It is clear that the voltage across the junction increases.
Now, what happens to (the width of) the depletion region? I would say, it decreases, because the electrons move from the p-region to the n-region, and the depletion region was originally formed by electrons going from n to p ("annihilating" holes in the p-section), which is now partially being undone. Yet I think sources are saying the region increases. What is the truth? And if I'm wrong, could anybody tell me why it increases (using the motions of the charge carriers).
For simplicity's sake, let's take a np junction.
Say we connect the left side (n-pole) to a POSITIVE voltage; this is called a reverse bias, because it will result in a small current from n to p. In other words: electrons will travel from p to n across the junction (and holes will go from n to p, but let's just talk about the electron movement to keep it clear). It is clear that the voltage across the junction increases.
Now, what happens to (the width of) the depletion region? I would say, it decreases, because the electrons move from the p-region to the n-region, and the depletion region was originally formed by electrons going from n to p ("annihilating" holes in the p-section), which is now partially being undone. Yet I think sources are saying the region increases. What is the truth? And if I'm wrong, could anybody tell me why it increases (using the motions of the charge carriers).