Oxide-free aC/Zr_0.65Al_0.075Cu_0.275/aC phase plates for transmission electron microscopy

Area of Science:

• Materials Science
• Physics
• Chemistry

Background:

• Thin-film phase plates (PP) are crucial for transmission electron microscopy (TEM) imaging of organic specimens.
• Conventional amorphous carbon (aC) PPs degrade rapidly under electron beam irradiation, limiting their operational lifetime.
• There is a need for alternative PP materials with enhanced stability and durability for advanced TEM applications.

Purpose of the Study:

• To develop and evaluate novel thin-film phase plates using a metallic glass alloy for improved TEM imaging.
• To investigate the material properties and performance of Zr_0.65Al_0.075Cu_0.275 (ZAC) as a phase plate material.
• To address the challenges of surface oxidation in ZAC and demonstrate its utility in phase-contrast TEM.

Main Methods:

• Fabrication of thin-film PPs using the metallic glass alloy Zr_0.65Al_0.075Cu_0.275 (ZAC).
• Encapsulation of ZAC films with thin amorphous carbon (aC) layers (aC/ZAC/aC system) to prevent surface oxidation.
• Fabrication of Zernike and Hilbert phase plates from the aC/ZAC/aC layered system.
• Phase-contrast TEM imaging of carbon nanotubes using the fabricated ZAC-based PPs.

Main Results:

• The ZAC alloy exhibits beneficial properties for phase plate applications, including a large inelastic mean free path.
• The aC/ZAC/aC layered structure effectively prevents surface oxidation of the ZAC alloy, maintaining its electrical conductivity.
• Zernike and Hilbert PPs fabricated from the aC/ZAC/aC system demonstrated successful phase-contrast TEM imaging.
• Significant contrast enhancement was observed for carbon nanotube samples imaged with the new phase plates.

Conclusions:

• Thin-film phase plates fabricated from the ZAC metallic glass alloy offer a promising alternative to conventional aC PPs.
• The encapsulation strategy effectively mitigates oxidation issues, enabling stable and reliable performance of ZAC PPs.
• These novel PPs provide enhanced contrast for imaging delicate organic and nanostructured materials in TEM.