NCEM National Center for Electron Microscopy: Microscopes and Facilities: OAM

TEAM 0.5

The TEAM 0.5 microscope is a double-aberration-corrected (scanning) transmission electron microscope (STEM/TEM) capable of producing images with 50 pm resolution. The basic instrument is a modified FEI Titan 80-300 microscope equipped with a special high-brightness Schottky-field emission electron source, a gun monochromator, a high-resolution GIF Tridiem energy-filter, and two CEOS hexapole-type spherical aberration correctors. The illumination aberration corrector corrects coherent axial aberrations up to 4th order, as well as 5th order spherical aberration and six-fold astigmatism. The imaging aberration corrector fully corrects for coherent axial aberrations up to 3rd order and partially compensates for 4th and 5th order aberrations. The microscope has two 2048x2048 slow-scan CCD cameras; one is bottom mounted and one is the GIF camera. A double-tilt holder (alpha<±30°, beta<±20°) and a dedicated single-tilt tomography holder (alpha<±75°) are available. The microscope can be operated either at 80 kV or 300 kV in the following modes:

- High-resolution TEM with acquisitions suitable for focal-series reconstructions

- High-resolution STEM (HAADF detector) also suitable for depth sectioning

- Energy filtered imaging and high-resolution electron energy-loss spectroscopy

- Electron TEM/STEM tomography

TEAM 0.5 Publications

Contact: Rolf Erni

Specifications 300 kV
	Monochromator ON	Monochromator OFF
Information limit	0.05 nm (at 0.15 eV)	0.08 nm
STEM resolution	0.1 nm	0.05 nm
Energy resolution (EELS)	0.15 eV	0.8 eV

TEM 3^rd order spherical aberration	<1 µm, adjustable (± 50 µm)
TEM 5^th order spherical aberration	~5 mm
STEM 3^rd order spherical aberration	<0.5 µm
STEM 5^th order spherical aberration	<0.5 mm

Specifications 80 kV
	Monochromator ON	Monochromator OFF
Information limit	0.07 nm (at 0.2 eV)	0.15 nm
STEM resolution	0.2 nm	0.14 nm
Energy resolution (EELS)	0.15 eV	0.8 eV

TEM 3^rd order spherical aberration	<1 µm, adjustable (± 50 µm)
TEM 5^th order spherical aberration	~8 mm
STEM 3^rd order spherical aberration	<1 µm
STEM 5^th order spherical aberration	<5 mm

	HAADF STEM images of gold [111] HAADF STEM images of a faceted grain boundary in a Au bicrystal viewed along the [111] direction (a). A buried boundary segment becomes visible only when the probe is focused 7 nm into the sample (b). A schematic of this geometry is shown in (c). 300 kV, probe semi-convergence angle: 35.6 mrad, inner detector angle ~50 mrad.
	STEM performance a) Annular dark field STEM image of hexagonal GaN [211]; crystal structure shown in the inset indicates Ga dumbbell spacing of 63 pm in this projection. b) Fourier transform of the image; image Fourier components extend to below 50 pm. c) Line trace across GaN dumbbells revealing 63 pm atom column separations. d) Single pixel line profiles from image Fourier transforms, shown here for Au [111] and GaN [211], demonstrating image Fourier components below 50 pm with S/N ratios around 3.
	TEM Young's fringe experiments with gold nanoparticles suspended on a carbon grid. a) With the monochromator switched off, the fringes extend to about 70 pm. b) With the monochromator switched on, the fringes extent to below 50 pm. The inset line traces are taken from the areas outlined in green and red boxes and show that the fringes extend beyond 50 pm when the monochromator is switched on. In the line traces, the periodicity of the Young's fringes is marked with dashed lines. The arrow indicates where the green trace crosses the 50 pm circle.
	(a) Direct image of a single-layer graphene membrane (atoms appear white). (b) Contrast profile along the dotted line in panel a (solid) along with a simulated profile (dashed). The experimental contrast is a factor of 2 smaller: Panel c shows the same experimental profile with the simulated contrast scaled down by a factor of 2. (d and e) Step from a monolayer (upper part) to a bilayer (lower part of the image), showing the unique appearance of the monolayer. Panel e shows the same image with an overlay of the graphene lattice (red) and the second layer (blue), offset in the Bernal (AB) stacking of graphite. In the bilayer region, white dots appear where two carbon atoms align in the projection. (f) Numerical diffractogram, calculated from an image of the bilayer region. The outermost peaks, one of them indicated by the arrow, correspond to a resolution of 1.06 Å. The scale bars are 2 Å.
	Graphene at 80kV. Phase of the electron exit wave function reconstructed from 15 lattice images.

TEAM 0.5 Publications