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Published on: June 16, 2014
Towards hot electron mediated charge exchange in hyperthermal energy ion-surface interactions
M P Ray1, R E Lake, L B Thomsen
1Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA.
Summary
Investigating ion-surface interactions on metal-oxide-semiconductor devices reveals atomic displacement as the primary energy loss mechanism for sodium ions. This finding aids in understanding hot electron dynamics for surface reactions.
Area of Science:
- Surface Science and Materials Science
- Ion-Solid Interactions
- Semiconductor Physics
Background:
- Solid-state tunnel junctions, comprising ultrathin metal-oxide-semiconductor (MOS) films, can generate hot electrons.
- These hot electrons are valuable for driving surface chemical reactions.
- Understanding ion-surface interactions is crucial for characterizing and optimizing such devices.
Purpose of the Study:
- To measure and analyze the energy loss of incident sodium (Na+) and helium (He+) ions on solid-state tunnel junction surfaces.
- To identify the dominant mechanisms responsible for energy loss, specifically atomic displacement and electronic excitations.
- To validate theoretical models against experimental observations of ion-surface interactions.
Main Methods:
- Utilized ultrathin film MOS devices as targets for ion bombardment.
- Employed ion scattering experiments with Na+ and He+ ions.
- Applied binary collision approximation and a non-adiabatic model to analyze ion-surface interactions and energy loss.
Main Results:
- Experimental energy loss measurements for Na+ ions were successfully reproduced using theoretical models.
- Atomic displacement of gold (Au) atoms within the MOS thin film was identified as the primary energy loss mechanism for Na+ ions.
- Electronic excitations also contribute to the overall energy loss, though to a lesser extent than atomic displacement for Na+.
Conclusions:
- The study elucidates the fundamental mechanisms governing ion-surface interactions on MOS tunnel junctions.
- Atomic displacement is the predominant pathway for energy dissipation when Na+ ions interact with the Au-containing thin film.
- Proposed neutral particle detection of scattered flux from biased devices as a potential method for studying hot electron-mediated charge exchange.
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