Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV

Abstract

Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

Electron radiation damage mechanisms in 2D MoSe2

“…For the confidence intervals we took √ N for N, √ V for V, and 1% for the electron dose were assumed. The values for the damage-cross-section of MoS2 were taken from 15 (4) 0.008 (3) of the total damage production. Taking into account that 24% of the damage is produced by knock-on damage, 63% by heat, charge and/or electronic excitations, then 13% of the damage has to be produced by other mechanisms, such as chemical etching and further ionization effects.…”

“…Modern transmission electron microscopes (TEM) allow imaging materials at a single atom resolution with acceleration voltages in the range of 20-300 kV [1][2][3] , foremost thanks to the practical realization of aberration correctors (AC) for transmission electron microscopy 4,5 . However, high electron doses are required for achieving a high enough signal to noise ratio for accurate detection of the atom position in the image.…”

Development of compact Cs corrector for desktop electron microscope

“…For a round lens, the paraxial ray trajectory r(z) derived from equations (3) can be reduced to the equation (6). In equation (6), η is the charge to mass ratio.…”

“…In the past decade, it has been demonstrated that the aberration-corrected scanning transmission electron microscopes (STEM) reaches sub-angstrom resolution [1] with sensitivity that is sufficient to detect even single light atoms [2]. The success of the aberration corrector motivates the development trend toward low voltage electron microscope (LVEM) for radiation sensitive materials, while maintaining high resolution [3][4][5][6]. The desktop STEM without aberration corrector operated at low voltage is available in the recent years [7].…”

Automatic software correction of residual aberrations in reconstructed HRTEM exit waves of crystalline samples

“…Hardware aberration correction for electron beams in transmission electron microscopy (TEM) is now widespread, substantially improving the interpretable resolution in TEM micrographs [1–4]. This technology is enabled by the combination of two factors; the ability to accurately measure optical aberrations in the electron beam, and a system of multipole lenses that can compensate for these measured aberrations.…”