Exam

The exam is now scheduled, see the info below

FYS3400, Spring 2020, final examination 

1. Periodic lattices as a result of the interatomic force balance in solids: basic ideas and specific interpretation of the ionic bonding, e.g. in NaCl.
2. Defects in crystals; case of vacancies ¨C reason to occur and equilibrium concentration.
3. Interpretation of the x-ray diffraction in reciprocal space; Laue condition; Bragg planes; Brillouin zones (BZs).
4. Atomic vibrations in infinite periodic lattices; dispersion relation - ¦Ø(k) and group velocity - v_g(k) in the 1-st BZ of 1D crystal.
5. Quantization of vibrations; restrictions on k-numbers because of the boundary conditions; phonon density of states (DOS) as a function of k and ¦Ø in 3D.
6. Lattice heat capacity; evaluation of different models.
7. Lattice thermal conductivity; analysis at ¡°low¡± and ¡°high¡± temperatures.
8. Free Electron Gas (FEG) model for electrons in solids: success and limitations.
9. 3D Free Electron Fermi Gas (FEFG) in the ground state - energy dispersion and DOS.
10. FEFG k-space in quantum wells and quantum wires and the corresponding DOS.
11. FEFG at T>0 and its heat capacity in 3D; explanation of the chemical potential (?).
12. Energy bands in periodic lattices; the ¡°molecular orbital¡± and the ¡°electron wave diffraction¡± reasoning; metal vs insulators; reasons for the band overlap. 
13. Effective mass method, re-organizing the electron-lattice interaction into the effective mass (m*) parameter allowing to use the FEFG formalism exchanging m with m*; interpretations of m*>0 and m*<0.
14. Hydrogen-like defects; finding electron orbits and energies for hydrogen in vacuum and extending the model for a defect in a semiconductor.
15. Electrons and holes in semiconductors; intrinsic and extrinsic carriers; qualitative explanation of the variations in ? as a function of temperature, doping, illumination.
16. p-n junction; balance between diffusion and drift currents for electrons and holes; application of the forward or reverse external bias.