SPEAKER:
Dr. Marjorie Olmstead
Department of Physics
University of Washington

TITLE:
"Building Atomic Bridges: Kinetics and Thermodynamics of Interface
Formation"

ABSTRACT:
As microelectronics yields to nanotechnology, interfaces between disparate
materials play a dominant role in device fabrication and performance.
Macroscopic properties of these structures are determined in large part by
atomic-scale interactions during interface formation.  These interactions
are set by thermodynamics, but can be (at least partly) controlled by
kinetics.  This talk will present examples of different phenomena arising
during interface formation between materials with dissimilar atomic size
(Ge/Si), valence (GaSe/GaAs, GaSe/Si), and ionicity (GaSe/Al2O3 and
CaF2/Si).   Rarely does one material form neat atomic layers atop another.
Rather, interdiffusion, interface compound formation and/or island growth
dominate.  Interfaces can also stabilize crystal structures not found in
bulk form or force a choice between two bulk structures.   Once metastable
structures are formed, stability is crucial to their exploitation in
commercial devices.  For example, buried CaF2/Si interfaces can change
dramatically when the CaF2 surface is altered, changing the barriers to
electron transport through the interface.