So in a diode in forward biased condition the electron from n side recombines with the hole in p side.I also understood that the electrons in n type are in conduction band and holes in p type are in Valence band.So inorder to a conduction band electron to recombine with a hole they should lose that extra energy right?

So my question is, do electron actually (1) lose their energy to fall into the holes or (2) they just bump each other(electrons and holes) randomly on application of voltage to recombine.If it is the second case then where does the energy go?

I don't understand when the textbooks say "electrons and holes recombine",with no energy level specifications.


1 Answer 1


(1) is correct. The energy is released as a photon.

  • $\begingroup$ Thank you for answering.Can you also explain how energy is released in normal diode as we don't see light in normal pn junction diodes.Also can you explain why electrons lose their energy in the diode even though there is a voltage provided? $\endgroup$
    – Hari
    Jun 28, 2020 at 17:16
  • $\begingroup$ For a direct-gap material, that is generally true. For indirect materials, such as Si, you need a phonon. $\endgroup$
    – Jon Custer
    Jun 29, 2020 at 20:02

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