- #1
MicheleC88
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Hi everybody. I'm new here and, first of all, sorry for my bad english :-D
I'm studying photoelectric absorption in semiconductors.
The book (and professor too) says that, in the conservation law:
ki + kph = kf
(where ki and kf are wave vectors of initial and final electron state, and kph is the wave vector of incoming photon) we can neglect kph because it is ≈ 2π/λ, whereas ki and kf are ≈ 2π/a, and λ>>a. (a is the length of unitary cell in real space).
But I think that this assumption is good only if electron is at the edge of Brillouin Zone; if the initial and final electrons are near [itex]\Gamma[/itex]-point, they should have a very little wave vector, comparable with kph, making the approximation not valid.
what is wrong in my words?
I'm studying photoelectric absorption in semiconductors.
The book (and professor too) says that, in the conservation law:
ki + kph = kf
(where ki and kf are wave vectors of initial and final electron state, and kph is the wave vector of incoming photon) we can neglect kph because it is ≈ 2π/λ, whereas ki and kf are ≈ 2π/a, and λ>>a. (a is the length of unitary cell in real space).
But I think that this assumption is good only if electron is at the edge of Brillouin Zone; if the initial and final electrons are near [itex]\Gamma[/itex]-point, they should have a very little wave vector, comparable with kph, making the approximation not valid.
what is wrong in my words?