Energy and charge dynamics in ion-irradiated surfaces and 2D materials from first principles

Kononov, Alina

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Description

Title

Energy and charge dynamics in ion-irradiated surfaces and 2D materials from first principles

Author(s)

Kononov, Alina

Issue Date

2020-07-14

Director of Research (if dissertation) or Advisor (if thesis)

Schleife, Andre

Doctoral Committee Chair(s)

Wagner, Lucas K

Committee Member(s)

• Mason, Nadya
• Bellon, Pascal

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• surfaces
• 2D materials
• TDDFT
• time-dependent density functional theory
• ion radiation
• graphene
• aluminum
• electron density analysis
• numerical time-stepping
• stopping power
• electron emission
• charge capture
• charge transfer
• charge dynamics
• emission threshold
• ion channel
• surface plasmon

Abstract

Materials experience ion radiation in a variety of contexts including cosmic rays in space and focused ion beams in high-resolution imaging and patterning techniques. While most existing knowledge concerning an energetic ion's interaction with solids is limited to bulk materials, many real-life radiation effects inherently involve surface processes such as electron emission. The extreme case of ion-irradiated 2D materials is particularly compelling given their myriad potential applications which rely on precise control of defects. First-principles simulations can characterize the elusive fundamental physics of ion-irradiated surfaces and inform ion beam microscopy and patterning techniques for 2D materials. Accurately modeling the sub-fs excited electron dynamics occurring as an energetic ion impacts a material requires time-dependent density functional theory, and the large simulation cells needed to treat the material-vacuum interface exacerbate the high computational cost of this method. Thus, special efforts were dedicated to improving the numerical algorithms used for evolving the system over time. Then, using this first-principles approach and novel electron density analysis techniques, this thesis investigated surface behavior in proton-irradiated aluminum, including an interesting deviation from bulk electronic stopping power and emitted electron escape depths. This framework was then applied to study ion-irradiated graphene, providing detailed information about sensitivity of energy deposition and electron emission to projectile parameters and offering insights into defect formation mechanisms mediated by electronic excitations. This thesis establishes a predictive approach for theoretical studies of ion-induced charge dynamics in 2D systems with important implications for optimizing focused ion beam techniques in nanotechnological applications.

Graduation Semester

2020-08

Type of Resource

Thesis

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Copyright and License Information

Copyright 2020 Alina Kononov

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