- #1
EmilyRuck
- 136
- 6
Hello!
Some of the processes caused by a pn junction are not clear for me. Just after the contact between the p and the n region, a migration of charges happens in a semiconductor junction in order to reach an equilibrium condition. A valence band and a conduction band are present in both regions.
Initially, the p-region valence band is partially filled with holes and the conduction band is empty. The n-region conduction band is partially filled with electrons and the valence band is full.
After the contact:
1) Electrons migrate from the conduction band in n-region to the conduction band in the p-region and then recombine with holes by decreasing their energy?
2) Holes migrate from the valence band in the p-region to the valence band in the n-region and then the remaining electrons in the n-region conduction band recombine with them?
If 1 and 2 are true, how can electrons spontaneously go from a conduction band with a lower energy to a conduction band with a higher energy? (With reference to http://ecee.colorado.edu/~bart/book/book/chapter4/gif/fig4_2_3.gif figure).
And the recombination phenomena (electrons that drop from conduction band to valence band, emitting a photon/phonon depending on the material) present in both the p and n regions?
Thank you,
Emily
Some of the processes caused by a pn junction are not clear for me. Just after the contact between the p and the n region, a migration of charges happens in a semiconductor junction in order to reach an equilibrium condition. A valence band and a conduction band are present in both regions.
Initially, the p-region valence band is partially filled with holes and the conduction band is empty. The n-region conduction band is partially filled with electrons and the valence band is full.
After the contact:
1) Electrons migrate from the conduction band in n-region to the conduction band in the p-region and then recombine with holes by decreasing their energy?
2) Holes migrate from the valence band in the p-region to the valence band in the n-region and then the remaining electrons in the n-region conduction band recombine with them?
If 1 and 2 are true, how can electrons spontaneously go from a conduction band with a lower energy to a conduction band with a higher energy? (With reference to http://ecee.colorado.edu/~bart/book/book/chapter4/gif/fig4_2_3.gif figure).
And the recombination phenomena (electrons that drop from conduction band to valence band, emitting a photon/phonon depending on the material) present in both the p and n regions?
Thank you,
Emily