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FEI Tecnai F20 S/TEM

The Tecnai F20 system is a field emission 200kV S/TEM with an X-TWIN lens and high brightness field emission electron gun (FEG).  This lens allows a 30 degree tilt with a low background double tilt holder, and allows +/-70 degrees of tilt with the tomography holder, allowing for efficient collection of X-rays for elemental analysis down to the sub-nanometer level.  The EDS solid angle for collection is 0.3sr, this results in a factor of 3-4 improvement in EDS collection efficiency when compared to the more established S-TWIN configuration.  The system has a GIF which can be used between imaging and spectroscopy modes, in spectroscopy mode the energy resolution is routinely 0.8eV. Scanning Transmission Electron Microscopy (STEM) is a mode routinely used for analytical experiments, and the X-TWIN system has an enhanced STEM performance by incorporating a 1.0 mm probe Cs value.

The system can be used to analyze elemental compositions down to the sub-nm range. The GIF operation is embedded in the microscope user interface, so in TEM mode it is used just like a CCD camera by the operators. TEM Bright-Field resolution is 0.25nm point to point, with a line resolution of 0.12nm achievable. While the area of interest is centered, the mode of the microscope can be changed to STEM mode for analytical investigations, without losing the area of interest. STEM resolution is 0.18nm on the HAADF detector, and Spectrum Imaging can be performed where the STEM image, the EDS signal and the PEELS signal can all be obtained at the same time. This is a very powerful way to cross correlate the analytical techniques.

Each user has the ability to set up their own account, such that when they log out of the system, their settings are stored automatically. Upon logging in again, all the optical parameters, deflector settings, stigmators, alignments etc. are restored. This is a significant enhancement of productivity in a multi-user facility such as ours where more experienced microscopists share the system with novice users. It avoids having the 'gaps' in the booking sheets after the novice users (nobody wants to spend half their session re-aligning a microscope). In addition the first time a user starts operating the system, they start with the supervisor settings; which enables all users to get started quickly with a pre-aligned microscope.