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I am trying to get a feel for electrons in semiconductros (say GaAs) with regards to the bandstructure of the material. I understand that the velocity of the electron can be written as ~ d(Energy)/d(wavevector) so at band extrema such as Gamma-point or X-point this goes to zero.

However, what I would like to know is what is the difference between a Gamma-point electron in say GaAs compared to an X-point electron? From the band diagram it is clear that the X-point electron has a higher energy but after that I start to struggle. Does the electron at the X-point have a certain momentum but no velocity for example? And, how could a Gamma-point electron become an X-point electron (would it require phonons for the momentum)?

Finally, if an electron is between the Gamma and X-points in the bandstructure does this say something about the direction or position that the electron has in the real lattice?

If anyone can shed some light that would be very helpful

Cheers

Stu

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# Gamma and X point electrons in semiconductors

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