FEI Tecnai G2 F20 ST S/TEM

An FEI Co. Tecnai G2 F20 S-Twin 200keV field-emission Scanning Transmission Electron Microscope (S/TEM) was installed in March 2005. 

The super twin lens allows for 80° tilt and a point to point resolution of 0.16nm.  A 1nm STEM probe allows for an imaging resolution of 0.19nm, and a high angle annular dark field detector (HAADF) allows for Z-contrast imaging in STEM mode at high resolution. 

High resolution analytical capabilities are provided on the TF20 STEM.  It is equipped with an EDAX energy dispersive x-ray spectrometer (EDS), a NanoMegas TOPSPIN Precession Electron Diffraction (PED) acquisition system and Thermo Fisher CETA 16M digital camera and an on-axis Bright-Field/Dark-Field STEM detector. 


Instrument Specifications

Electron Source
  • Flexible high tension (20, 40, 80, 120, 160, 200 kV and values in between)
  • Schottky field emitter with high maximum beam current (> 100 nA)
  • High probe current (0.5 nA or more in 1 nm probe)
  • Small energy spread (0.7 eV or less)
  • Spot drift < 1 nm/minute
Specimen Stage
  • Fully computer-controlled, eucentric side-entry, high stability CompuStage
  • Maximized tilts for any X,Y,Z, α and β combination
  • Choice of a variety of specimen holders
  • X, Y movement ± 1 mm, Z movement ± 0.375 mm; specimen size 3 mm
  • Specimen recall reproducibility: ≤ 0.3 μm (after movement of 300 μm in x and y) and ≤ 0.1 (α tilt)
  • Drift ≤ 0.5 nm/minute with a standard holder attainable


  • Coma-free alignment for high resolution objective lens centering
  • Ranged, rotation-free magnification and diffraction series
  • Magnification reproducible within ± 1.5%
  • FEI CETA 16M CMOS Camera


  • Xplore3D™: FEI's intelligent tomography solution for TEM and STEM [CURRENTLY UNAVAILABLE]
  • TrueImage: FEI's patented focal series acquisition and reconstruction software package [CURRENTLY UNAVAILABLE]


  • Fully digital scan system
  • Bright Field and Annular Dark-Field Mode
  • High resolution STEM with HAADF detector

S-Twin Objective Lens

  • Information limit (nm) 0.14
  • Extended resolution (nm) 0.16
  • Minimum focus step (nm) 1.8
  • TEM magnification range 25x - 1,030kx
  • Camera length (mm) 30 - 4,500
  • Maximum diffraction angle ±13°
  • STEM HAADF resolution (nm) 0.19
  • STEM magnification range 150 x - 230 Mx
  • Maximum tilt angle with double-tilt holder ±40°
  • Maximum tilt angle with tomography holder  ±80°
  • EDS solid angle (srad) 0.13


  • Excellent EDS in-hole performance
    (< 1% hole count)
  • Low system background in EDS
    (< 1% spurious peaks)
  • High P/B ratio (Fiori number) > 4000
  • EDAX Octane T Optima 30mm2 SDD EDS