Notre Dame Integrated Imaging Facility

TITAN TEM

FEI Titan 80-300 is a state-of art  Transmission Electron Microscope (TEM) that operates in both transmission (TEM) and scanning transmission electron microscopy  (STEM) modes. The major specifications are the following:

 

• Operating voltages:  80 kV and 300 kV

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• TEM point-to-point resolution of 0.19 nm with information limit below 0.1 nm.

• Magnification from 45x up to 1, 250, 000x

• FEI Single Tilt Holder

• FEI Be Double Tilt Holder

• Gatan 4x4k bottom-mount CCD camera

• Oxford INCA 30 mm2 LN2 Energy Dispersive X-ray Spectroscopy (EDS) detector with 130 eV energy resolution

• Tridem Gatan Electron Energy Loss Spectroscopy (EELS) system with 0.7 eV energy resolution

 

The major capabilities of FEI Titan 80-300 include, but are not limited to:

  • TEM and HDAAF STEM Imaging on atomic level (with Angstrom level resolution)

  • Selected Area and Nano Electron Diffraction for crystal structure analysis

  •  Bright-field and Dark-filed Imaging in TEM and STEM modes

  •  Chemical composition analysis with EDS and EELS at nano-scale level

  • Energy Filtered imaging and Advanced energy resolution in EELS for band gap and fine structures analysis

For more information about FEI Titan 80-300 microscope or training schedule, please, contact Dr. S. Rouvimov

 

Examples of TEM results from FEI Titan 80-300 microscope

For more TEM results, please, visit our TEM Image Gallery

 

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MBE grown GaAs Nanowire

(Courtesy of Brendan O'Dowd & Prof. Jacek Furdyna, Department of Physics)

HREM image of GaAs nano-wire of wurtzite crystal structure.

Enlarged is area with crystal defects containing a thin lamella of sphalerite structure (Operator: Dr. S. Rouvimov) 

Inserted (Top left corner) is SEM image taken at Magellan SEM (Operator: Brendan O'Dowd)

 

 

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MBE grown GaN Quantum Wells in AlN matrix

(Courtesy of Jai Verma & Prof. Debdeep Jena, Department of Electrical Engineering)

HDAAF STEM image shows two sets of GaN Quantum Wells  which have different degree of interface roughness (due to intentionally different growth conditions). Note that Ga atoms  have brighter contrast as compared to Al atoms (Z-contrast).

Inserted is Atomic Resolution HDAAF STEM image of selected area   (Operator: Dr. S. Rouvimov)

 

A brief summary of some TEM diagnostic capabilities is listed below:

Energy-dispersive X-ray spectroscopy(EDS or EDX) is an analytical technique used for the elementalanalysis or chemical characterizationof a sample. It is one of the variants of X-ray fluorescencespectroscopywhich relies on the investigation of a sample through interactions between electromagnetic radiationand matter, analyzing X-raysemitted by the matter in response to being hit with charged particles. Its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structureallowing X-rays that are characteristic of an element's atomic structure to be identified uniquely from one another. Allows to detect all elements with atomic number 5 (B) and higher with space resolution 0.136 nm

In electron energy loss spectroscopy (EELS) a material is exposed to a beam of electronswith a known, narrow range of kinetic energies. Some of the electrons will undergo inelastic scattering, which means that they lose energy and have their paths slightly and randomly deflected. The amount of energy loss can be measured via an electron spectrometerand interpreted in terms of what caused the energy loss. Inelastic interactions include phononexcitations, inter and intra band transitions, plasmonexcitations, inner shell ionizations, and Čerenkov radiation. The inner-shell ionizations are particularly useful for detecting the elemental components of a material. Within transmission EELS, the technique is further subdivided into valence EELS (which measures plasmons and interband transitions) and inner-shell ionization EELS (which provides much the same information as EDS, but from much smaller volumes of material.

Electron diffraction via the transmission electron microscope is a powerful method for characterizing the structure of materials, including perfect crystals and defect structures. The periodic structure of a crystalline solid acts as a diffraction grating, scattering the electrons in a predictable manner. Working back from the observed diffraction pattern, it may be possible to deduce the structure of the crystal producing the diffraction pattern. Apart from the study of crystals i.e. electron crystallography, electron diffraction is also a useful technique to study the short range order of amorphoussolids. Whereas both the execution of powder X-ray (and neutron) diffraction experiments and the data analysis are highly automated and routinely performed, electron diffraction requires a much higher level of user input.

For more information, please contact