Three dimensional analysis of the composition in solid alloys by variable probe in scanning transmission electron...

Area of Science:

• Materials Science
• Analytical Chemistry
• Solid State Physics

Background:

• Accurate determination of atomic composition and distribution in materials is crucial for understanding their properties.
• Conventional methods often struggle with quantitative 3D reconstruction and incorporating complex phenomena like channeling effects.

Purpose of the Study:

• To develop a novel mathematical framework for quantitative, column-by-column atomic reconstruction using STEM.
• To enable the 3D distribution analysis of guest atoms within a host matrix.
• To incorporate channeling effects, often neglected, into atomic distribution reconstruction.

Main Methods:

• Utilized scanning transmission electron microscopy (STEM) with high-angle annular dark-field (HAADF) imaging.
• Developed a new mathematical framework for joint analysis of experiments with variable beam convergence and/or defocus.
• Applied the method to dynamic simulations of Indium Gallium Nitride (InGaN) alloy to assess reliability and limitations.

Main Results:

• Successfully reconstructed atomic distribution along imaged columns from measured intensity.
• The framework accounts for probe intensity dependence on depth and incorporates channeling effects.
• Demonstrated the method's capability to systematically vary beam convergence for channeling oscillation control.

Conclusions:

• The proposed mathematical framework offers a robust approach for quantitative 3D atomic reconstruction in materials.
• This technique overcomes limitations of previous methods by including channeling effects.
• The study defines the reliability and limitations of this advanced STEM-based reconstruction method.