Date of Award
Doctor of Philosophy
Physics and Astronomy
Condensed Matter Physics
Michael C. Tringides
This thesis covers PhD research on two systems with unique and interesting physics. The first system is lead (Pb) deposited on the silicon (111) surface with the 7x7 reconstruction. Pb and Si are mutually bulk insolubility resulting in this system being an ideal case for studying metal and semiconductor interactions. Initial Pb deposition causes an amorphous wetting layer to form across to surface. Continued deposition results in Pb(111) island growth. Classic literature has classified this system as the Stranski-Krastanov growth mode although the system is not near equilibrium conditions. Our research shows a growth mode distinctly different than classical expectations and begins a discussion of reclassifying diffusion and nucleation for systems far away from the well-studied equilibrium cases.
The second system studied investigates the interactions of the Rare Earth metal Dysprosium (Dy) with a carbon based 2D lattice called graphene. Graphene is a 2D material composed of carbon atoms arranged in hexagons, similar to a honeycomb with carbon atoms at each corner. The graphene we used is grown epitaxially from a substrate of silicon carbide. This creates a multilayered playground to study how metals interact both on the surface of graphene and intercalated in between graphene layers. Many types of atoms have been studied in graphene systems, but the rare earths and in particular Dy have not been well investigated. This thesis contributes to the knowledge base of graphene on SiC structure and metal-graphene interactions.
These systems have been investigated in ultra-high vacuum (UHV) environments with base pressures around 5.0x10^-11 torr. The Pb/Si(111)-7x7 system was investigated with scanning tunneling microscopy (STM) and the Graphene/SiC system was investigated with both STM and Spot Profile Analyzing Low Energy Electron Diffraction (SPA-LEED).
Hershberger, Matthew, "Nanostructure control: Nucleation and diffusion studies for predictable ultra thin film morphologies" (2017). Graduate Theses and Dissertations. 15318.