Unformatted text preview: None of the above. (continued on next page) 1 5) Electron electron scattering is often treated to first order by assuming an equilibrium (Maxwellian or Fermi Dirac) distribution with one change. What is the change? a) The Fermi level is replaced by the quasi Fermi level. b) The lattice temperature is replaced by the electron temperature. c) The magnitude of the distribution is re normalized. d) The Fermi function is replaced by the Bose Einstein function. e) None of the above. (the assumption here is that we are still near equilibrium) Lecture 27 Quiz: 1) When we write the collision integral in the Relaxation Time Approximation, ( f − fS ) , ˆ Cf ( r , p, t ) = − τ f (r , p)
what is the characteristic time, τ f ? a)
b)
c)
d)
e) The scattering time. The momentum relaxation time. The energy relaxation time. All of the above. None of the above. 2) When we write the collision integral in the Relaxation Time Approximation, ( f − fS ) , ˆ Cf ( r , p, t ) = − τ f (r , p)
why do we use f S rather than the equilibrium, f0 ? a) Because we are not exactly at equilibrium. b) To be sure that the number of carriers is conserved. c) To the sure that the moment...
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 Fall '14

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