Surface Science: Principles and Applications

Surface Science: Principles and Applications

The performance characteristics and functions of nowadays and emergent devices is basically defined by the surfaces and interfaces constituting these devices. This is easy to apprehend, especially when considering size reduction of components down to nanometer size, where surfaces/interfaces constitute most of the devices. Such advancement in technology has been made possible by the emergence of so-called “Surface Science” studies over the last ~ 50 years. In this context, the point of this lecture is to provide the students with an overview of what surface science is. This lecture addresses the general properties of surfaces, from a structural and (opto)electronic point of view.

Below, the details of the points that will discussed:

Introduction:
-        What is surface science

-        Why surface science is important

-        Historical development

Structural properties:

1.      Basic crystallographic properties of surfaces

-        The basics of crystallography (e.g., unit cell, Bravais lattice, Wigner Seitz cells, indexation of the planes) that are needed for discussion in the context of surfaces.

-        The basics to describe the real space structural properties of surfaces

-        Going from real to reciprocal space and application by diffraction at surfaces with low energy electron diffraction

2.      Structural properties of surfaces:

-        The properties of real (model) surfaces (metal and semiconductor). Description of important surface reconstructions and impact on the surface electronic properties. Principles driving surface reconstruction.

-        Atomic structure of surfaces covered with adsorbates: interface structural properties, determination of surface phase composition…

3.      Structural defect at surfaces:

-        General considerations (structure, energy formation, …) about defects at surfaces (step edges, adatoms, vacancies, etc.)

4.      Adsorption and desorption

Optoelectronic properties:

1.      Recalling basics of solid states physics (e.g. Drude model, free and nearly-free electron model, density of states)

2.      Derivation of the dielectric function of a free electron gas and of bound electrons and application to spectroscopy

3.      Electronic properties of surfaces:

-        condition for the emergence of surfaces states and the different types of surface states

-        surface states at metal and semiconductor surfaces and correlation with surface reconstruction

-        significance of surface states at semiconductor surfaces

Experimental techniques to investigate surfaces:

-        Scanning tunneling microscopy (STM), low-energy electron diffraction (LEED)

-        X-ray- and UV- Photoemission (XPS, UPS)

-        Ultra-high vacuum technologies