Volta potential phase plate for in-focus phase contrast transmission electron microscopy

Area of Science:

• Materials Science
• Electron Microscopy
• Surface Physics

Background:

• Conventional Zernike phase plates in transmission electron microscopy (TEM) can suffer from alignment issues and fringing artifacts.
• Understanding beam-matter interactions is crucial for developing advanced TEM components.

Purpose of the Study:

• To introduce and characterize a new type of phase plate for TEM based on a beam-induced Volta potential.
• To demonstrate the advantages of this Volta phase plate (VPP) over existing technologies.

Main Methods:

• Utilizing a continuous thin film that generates a negative, beam-induced Volta potential when heated to ~200 °C.
• Implementing the phase shift "on the fly" using the central diffraction beam, negating the need for precise alignment.
• Comparing image quality and artifacts with those obtained using a Zernike phase plate.

Main Results:

• The VPP produces higher contrast images compared to Zernike phase plates.
• No fringing artifacts were observed in images acquired with the VPP.
• The VPP exhibits a stable phase shift after an initial one-week settling period and demonstrates a long service life (>6 months).

Conclusions:

• The Volta phase plate (VPP) is a stable and effective component for transmission electron microscopy, offering improved image contrast and artifact reduction.
• The VPP leverages a beam-induced Volta potential, a phenomenon related to, but constructively used differently than, Zernike phase plate degradation mechanisms.
• Further research is needed to fully elucidate the underlying physics and chemistry of the Volta potential generation, likely involving radiation-induced surface modification and surface-gas interactions.