Tiny Bubbles: Combined HR(S)TEM and 4D-STEM Analysis of Sub-Nanometer He Bubbles in Au

Area of Science:

• Materials Science
• Nanotechnology
• Physics

Background:

• Irradiation creates defects of various sizes in materials, including those smaller than one nanometer.
• Characterizing these nanoscale defects is crucial for understanding material behavior under extreme conditions.
• High-resolution scanning transmission electron microscopy (HRSTEM) can image atomic structures, while four-dimensional STEM (4D-STEM) provides larger field-of-view defect quantification.

Purpose of the Study:

• To present a combined HRSTEM and 4D-STEM approach for defect characterization.
• To study helium (He) bubble formation in an irradiated gold (Au) thin film.
• To demonstrate effective characterization of sub-nanometer irradiation defects.

Main Methods:

• Utilized a combined HRSTEM and 4D-STEM imaging technique.
• Applied the method to a model system of He bubble implantation in an Au thin film.
• Analyzed defect sizes, distributions, and associated strain fields.

Main Results:

• Successfully imaged and characterized sub-nanometer He bubbles, which are often below the resolution limit of conventional methods.
• Quantified the distribution of He bubbles and larger irradiation defects within the Au film.
• Demonstrated the capability of the combined technique to analyze materials across a representative volume.

Conclusions:

• The combined HRSTEM and 4D-STEM approach is effective for characterizing nanoscale defects, including sub-nanometer He bubbles.
• This methodology is valuable for studying materials subjected to irradiation and extreme environments.
• The technique provides a comprehensive understanding of defect populations and their impact on material properties.