Surface Physics 1

The learning objectives are:. to develop knowledge on the theory and phenomenology of surfaces in general, covering both classical and quantum descriptions, and developing specific knowledge and individual in-depth skills.
The teaching is also aimed at providing the student with the tools necessary to understand the
scientific literature at the state-of-the-art.

At the end of the course the student must know:

1. The relevance and the role played by Surface Physics in the main developments of Condensed Matter Physics over the past 50 years;

2. The physical reasons that make it necessary, for the realization of many experiments in Surface Physics, to work in the so-called Ultra High Vacuum (UHV) conditions.

3. How to correctly set the problem of the stability of a solid surface from the thermodynamical point of view, and will be able to relate it to the concept of surface tension.

4. What are the main experimental techniques giving access to the direct lattice and / or to the reciprocal surface lattice.

5. The concepts associated with the applications of the two-dimensional Fourier transform in relation to the possible 2D periodic structures (the five Bravais lattices, their elementary cells, the two-dimensional Brillouin zone).

6. The physical mechanisms underlying the phenomena of Surface relaxation and Surface reconstruction. He will know the currently used notations for the identification of surface reconstructions, also in presence of adsorbates.

7. The principles of surface diffraction, and will be able to relate them to the analogous principles valid for diffraction by a three-dimensional lattice (Ewald sphere).

8. The main surface preparation techniques, with their relative fields of application, advantages and disadvantages: e.g . cleavage, ion sputtering, molecular beam epitaxy (MBE, CBE, MOCVD).

9. The phenomenology of the growth of thin films, and will know the main experimental techniques that allow their characterization.

10. The principles of operation of the low-energy electron diffraction technique (LEED); will be able to recognize some examples of LEED spectra; will know the advantages and limitations of LEED compared to other techniques.

11. The principles and potentialities of the Auger spectroscopy. He will be able to recognize some examples of Auger spectra.

12. Some principles of ion scattering-based techniques, such as Secondary Ion Mass Spectroscopy (SIMS) and Rutherford Backscattering (RBS).

13. The main stages of the discovery of scanning tunneling microscopy (STM). He will know the working principles, and the theoretical and phenomenological description (Tersoff and Hamann model). He will know the most classic application examples, such as the one on the (111) surface of Silicon with its famous (7x7) reconstruction.
He will also be aware of the technique known as atomic force microscopy (AFM) and its most common applications.

14. The reasons why the creation of a surface can induce the existence (otherwise unacceptable) solutions of the Schroedinger equation (surface states), and will know some examples of such solutions (e.g., Schockley, Tamm). He will be able to deduce the consequences and make the connection with the phenomena of Band narrowing and Surface Core-Level Shift.

15. The conditions under which the so-called Image States can be produced.

16. The phenomenon of surface optical reflectivity in the Fresnel scheme, and will know the origin of the deviations of the real reflectivity from the Fresnel-expected one.

17. The principles of optical spectroscopy based on reflection anisotropy (RAS) and differential reflectivity (SDR).

18. The concept of surface phonon, and surface vibrational resonances. He will know how to classify the surface phonons in terms of their polarization (SP, SH). He will be able to describe the vibrational behavior of a surface in the limit of the elastic continuum (Rayleigh wave and its applications).