Do carriers move across a p-n junction at 0 K?

In summary, the band diagram of a p-doped and n-doped semiconductor at 0 K shows that the surplus carriers are confined to their respective acceptor and donor levels. At this temperature, there are no free carriers in the system and recombination between electrons and holes should not occur. However, at higher temperatures, the acceptor and donor carriers would ionize and a depletion zone would form. It is unclear if a depletion zone would still form at 0 K, but it is important to consider the behavior as carrier kinetic energy approaches zero.
  • #1
Wrichik Basu
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Often a band diagram is used to explain what happens when two pieces of the same semiconductor, one p-doped, one n-doped, are put together. I am a little confused about it, so here is my question.

Initially and at ##0\mathrm{K}##, the surplus carriers should be confined to their respective acceptor and donor levels, e.g. the flatband diagram would look like follows:

HGBKU.png


Now, there are no free carriers in the system and thus, the electrons from the donor level should not be able to recombine with the holes from the acceptor levels due to spatial detachment.

Of course, provided some temperature, the acceptor and donor carriers would ionize and free carriers would be at disposal for recombination and thus, a depletion zone would form. But at ##0K## it seems to me that this should not happen. In reality, would a depletion zone be formed anyway somehow (are there other relevant physics taking action)?

Here, I'm considering the ideal case in which ##0K## exists. Let us not go into the discussion whether it practically exists or not.
 

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  • #2
At 0 K you can't have this electron distribution. Some donor electrons at the border have to fill some of the holes until there is an equilibrium.
 
  • #3
Ask instead how the behavior changes as the carrier kinetic energy approaches zero: what is the limiting case?
 

Related to Do carriers move across a p-n junction at 0 K?

1. How does the movement of carriers across a p-n junction change at 0 K?

The movement of carriers across a p-n junction is significantly affected by temperature. At 0 K, the carriers have very little thermal energy, which means they have a lower probability of overcoming the potential barrier at the junction. This results in a decrease in the movement of carriers across the junction.

2. Can carriers still move across a p-n junction at 0 K?

Yes, carriers can still move across a p-n junction at 0 K. However, their movement is significantly reduced compared to higher temperatures due to the decrease in thermal energy.

3. What is the role of the potential barrier in the movement of carriers across a p-n junction at 0 K?

The potential barrier at the p-n junction acts as a barrier for the movement of carriers. At 0 K, the carriers have very little thermal energy to overcome this barrier, which decreases their movement across the junction.

4. How does the movement of majority and minority carriers differ at 0 K?

At 0 K, majority carriers (electrons in n-type and holes in p-type) have a higher probability of crossing the potential barrier compared to minority carriers. This is because majority carriers have a higher concentration and therefore a higher chance of overcoming the barrier at 0 K.

5. Is the movement of carriers across a p-n junction at 0 K affected by the doping concentration?

Yes, the doping concentration does affect the movement of carriers across a p-n junction at 0 K. Higher doping concentrations result in a higher concentration of majority carriers, which increases their chances of crossing the potential barrier at 0 K. On the other hand, lower doping concentrations result in a lower concentration of carriers and therefore a decrease in their movement at 0 K.

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