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

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SUMMARY

The voltage drop across a diode decreases with increasing current due to the diode's dynamic resistance and the effects of charge carrier injection. In silicon diodes, as current increases, more charge carriers are injected into the depletion region, which alters the potential barrier. This behavior is quantitatively described by the Shockley equation, which models the current-voltage characteristics of diodes. Therefore, the observed change in voltage drop is a result of the non-ideal behavior of diodes under varying current conditions.

PREREQUISITES
  • Understanding of semiconductor physics, specifically P-N junctions
  • Familiarity with diode characteristics and the Shockley equation
  • Knowledge of current-voltage relationships in electronic components
  • Basic principles of charge carrier dynamics in semiconductors
NEXT STEPS
  • Study the Shockley equation in detail to understand its implications on diode behavior
  • Research the concept of dynamic resistance in diodes and its impact on voltage drop
  • Explore the effects of temperature on diode characteristics and voltage drop
  • Investigate different types of diodes and their current-voltage relationships
USEFUL FOR

Electrical engineers, physics students, and anyone involved in semiconductor device design or analysis will benefit from this discussion.

Alex Myhill
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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.
 
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Hi Alex, :welcome:

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

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