Why does the voltage drop across a diode change with increasing current?

[Alex Myhill]

Homework Statement

I have recently performed an experiment where the voltage drop and current through a diode were measured. I am wondering why the voltage drop across the diode changes. Theoretically, the voltage drop should stay the same as there is a certain amount of energy required to get past the depletion zone at the junction of the P-doped and N-doped silicon. Why then does the voltage drop change as the current increases?

Homework Equations

There are no relevant equations for this question.

The Attempt at a Solution

Does the voltage possibly increase due to the increase charge in the diode as the current increases? I am really not sure as everywhere I have read states that the voltage drop shouldn't change.

 

[BvU]

Hi Alex,

Check regions 3 and 4 here and the Shockley eqn right after that.