- #1
rwooduk
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Homework Statement
Homework Equations
None.
The Attempt at a Solution
I understand the question, for a phonon it can excite an electron from the valance band to the conduction band between any values of k. If it were a photon it could only excite the electron at specific k values.
Anyway so looking at the graph minimum/maximum looks (i tried differentiating Ec and Ev and setting to zero to find the exact minimum and maximum but it ended up getting complicated) like it is at k=0 for Ev and k=1 for Ec.
So now I need to put k=1 into the equation for Ec. And this is what I'm struggling with, so I put k=1 in and get $$E_{c} = 11 - 2\AA^{-2} + \AA^{-4} = 11 - \frac{2}{(10^{-10})^{2}}+ \frac{1}{(10^{-10})^{4}}$$ which must be wrong as the angstrom terms are really small and Ec goes massive.
Any advice on this would be appreciated.
edit the red AA's are angstroms, don't know why its not working