Aberration corrected STEM by means of diffraction gratings

Area of Science:

• Materials Science
• Physics
• Electron Microscopy

Background:

• Aberration correction technology has revolutionized atomic-scale materials analysis using electron microscopy over the last 15 years.
• Conventional methods rely on complex multipole electrodes and magnetic solenoids to correct inherent aberrations.

Purpose of the Study:

• To introduce and demonstrate an alternative, passive method for spherical aberration correction in scanning transmission electron microscopy (STEM).
• To present a nanofabricated diffractive optical element as a holographic device for aberration correction.

Main Methods:

• Installation of a passive, nanofabricated diffractive optical element (grating corrector - GCOR) in the probe forming aperture of a conventional electron microscope.
• Design of the holographic device to correct for spherical aberration and other complex aberrations in the electron's wave front.
• Proof-of-principle experiment to demonstrate the effectiveness of the GCOR in STEM.

Main Results:

• Successful correction of spherical aberration in STEM was achieved using the grating corrector (GCOR).
• Aberration-corrected high-resolution high-angle annular dark field (HAADF-) STEM images were recorded.
• Current probe current and resolution were not advanced in this initial demonstration.

Conclusions:

• The developed grating corrector (GCOR) provides a viable alternative for spherical aberration correction in STEM.
• This technology holds potential for economical aberration-corrected high-resolution STEM applications.
• Further improvements could enhance probe current and resolution, expanding its utility.