On one hand, my book calls both electrons and holes intrinsic charge carriers of a semiconductor, and on the other, it states the relation x = y = n, where x, y and n stand for the number of electrons, holes and intrinsic charge carriers respectively. Shouldn't it be n = x+y instead?


Normally what we call the intrinsic charge carrier concentration, that I note $n_i$ is the number of charge of any kind (not their) sum. It is a convention to build the theory nothing more. Having defined something like $n'_i = e + h$ would have make the equations much more ugly.

This will be of use latter, because even though the semiconductor is not intrinsic the relation

$$e\cdot h = n_i^2$$

will be verified.

Notice that your case verify this.

It is a terrible idea to use the notation $e, h$ (especially e) as it will be confused with the charge.

If you are new to semiconductors I recommend you to read the two dedicated chapters of Ashcroft and Mermin. They are clear and give a good baseground.


  • $\begingroup$ Thank you! That explains it all. $\endgroup$ – Boingboingboing Feb 2 at 13:05
  • $\begingroup$ @ZMeson - and please, please start now with treating electrons and holes as full equals - your life will be much easier. $\endgroup$ – Jon Custer Feb 2 at 14:56
  • $\begingroup$ @Jon Custer Noted. :) $\endgroup$ – Boingboingboing Feb 3 at 15:54

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