Transmission Electron Microscopy (TEM)
TEM at a Glance
TEM is a microscopy technique capable of providing very high resolution images down to a level of several Angstroms (~ 0.19nm). It images thin samples via the interaction of electrons as they pass through a specimen. Detecting a range of resultant secondary signals allows for the study of nano-scale morphological and chemical features of materials down to near atomic levels.
Right: JEOL 2100+ TEM at the NMRC
- Bright field imaging
- Electron diffraction
- Dark field imaging
- Energy Dispersive X-ray Spectroscopy (EDS)
- Electron Energy Loss Spectroscopy (EELS)
- Scanning Transmission Electron Spectroscopy (STEM)
- Nanotomography (3D profiling)
Images Courtesy of Vladimir Korolkov Photography and Lubrizol Ltd.
How does TEM work?
An electron source at the top of the microscope emits electrons that travel through a vacuum in the column of the microscope. Electromagnetic lenses are used to focus the electrons into a very thin beam and this is then directed through the specimen of interest. The electrons passing through the specimen then impact on a detector. Traditional bright field imaging relies on incident electrons being scattered and disappearing from the beam depending upon the compositional density and crystal orientation of the sample. The intensity of un-scattered electrons gives rise to a "shadow image" of the specimen, with different parts of a specimen displayed in varied darkness according to density. By rotating a sample, and taking multiple images at each rotation, it is also possible to build a 3D representation of the specimen (tomography).
The crystal structure of samples with regular atomic structure (crystalline material) may also be analysed via electron diffraction. Positive interference in the back focal plane leads to discreet spots of electron localisation, which can then be visualised by mapping the back focal plane to the imaging apparatus. The diffraction patterns can then be used to analyse to the crystal structure of the specimen.
X-ray emission consequent to the interaction of the primary electron beam with the sample, can also be detected by an energy-dispersive spectrometer (EDS) within the TEM. As the resulting X-ray energies are characteristic of the atomic structure of the element they originated from, the spectra generated can be used to identify the constituent elements.
It is also possible to measure the loss of energy from the inelastic scattering of electrons in specimen transmission (EELS). This information can be used to infer elemental composition, chemical bonding, valence and conduction band electronic properties.
Our TEM facilities
Hosted at the Nanoscale and Microscale Research Centre (nmRC).
JEOL 2100F FEG-TEM
- Field emission electron gun (FEG), providing a high brightness and high stability electron source for use at 100kV and 200kV.
- A point resolution of 0.19nm allows the ultrahigh resolution analysis of materials, on the nanometer scale.
- Bright Field STEM Detector.
- High Angle Annular Dark Field (HAADF) STEM Detector.
- Gatan Orius (4k x 2.6k) Camera with digital streaming video for high resolution and TV rate imaging.
- Gatan Tridiem Filter Spectrometer and 2K x 2K CCD camera, configured for use at 100kV and 200kV. Enables elemental mapping via Electron Energy Loss Spectroscopy (EELS) and Energy Filtered TEM (EFTEM).
- Oxford Instruments 80mm X-Max system for energy dispersive x-ray spectroscopy (EDS) analysis.
- Gatan Double Tilt Beryllium Holder with an x and y tilt to 35 degrees and low contrast background for EDS analysis.
- Room Temperature Tomography: Gatan 916 Room temp tomography holder with up to 80 degrees tilt. Allows tilt series acquisition to generate 3D images.
- Cryo-tomography and cryo transfer: Gatan 914 Cryo-tomography holder system including cold controller / cryo-workstation. Liquid nitrogen cooled holder, allows the investigation of heat sensitive and cryogenically frozen samples.
- Electrical holder. Gatan 636 DT analytical LN2 holder with temperature controller with EBIC stage option (4 electrical connections) plus Smart EBIC. Allows the electrical properties of samples to be related to the microstructure - e.g. defects in semiconductors.
- Heating holder. Gatan 652 Double tilt heating holder. Allows samples to be heated up to 1000 degrees in the TEM column.
JEOL 2100+ TEM
FEI Tecnai G12 12 Biotwin
- 120 kV LaB6 TEM for high contrast imaging.
- Gatan SIS Megaview IV digital camera.
- Tomography compustage for tomographic characterisation.
- Cryo-stage for low temperature observation of temperature dependent or hydrated samples.
- Ideal for low-contrast, beam-sensitive biological specimens, or other soft materials such as polymers.
JEOL 2000 FX TEM
- 200 kV analytical TEM.
- LaB6 or tungsten filament electron gun.
- Low background double-tilt sample holder and single-tilt sample holder for 2 samples.
- Orius digital camera for high resolution imaging.
- Oxford Instruments XMax 80 INCA EDS system.
- Photographic plate camera and RHEED stage for surface diffraction measurements.
Publications of Interest
- La Torre, A., del Carmen Gimenez‐Lopez, M., Fay, M. W., Lucas, C. H., Brown, P. D., & Khlobystov, A. N. (2015). Dynamics of Gold Nanoparticles on Carbon Nanostructures Driven by van der Waals and Electrostatic Interactions. Small, 11(23), 2756-2761.
- Pacella, M., Butler-Smith, P. W., Axinte, D. A., & Fay, M. W. (2014). FIB/TEM/EELS micro/nanometric investigations of the effects of laser ablation on the diamond/binder structure in polycrystalline diamond composites. Journal of Materials Processing Technology, 214(5), 1153-1161.
- La Rocca, A., Campbell, J., Fay, M. W., & Orhan, O. (2016). Soot-in-Oil 3D Volume Reconstruction Through the Use of Electron Tomography: An Introductory Study. Tribology Letters, 61(1), 1-11.
- La Rocca A., Di Liberto G., Shayler P.J., Fay M.W. (2013). The nanostructure of soot-in-oil particles and agglomerates from an automotive diesel engine. Tribology International. 61, 80–87
- La Torre A., Gimenez-Lopez M., Fay M., Rance G., Solomonsz W., Chamberlain T., Brown P., Khlobystov A. (2012). Assembly, Growth and Catalytic Activity of Gold Nanoparticles in Hollow Carbon Nanofibres. ACS Nano. 6(3) 2000-2007
- Edwards H.K., Fay M.W., Anderson S.I., Scotchford C.A., Grant D.M. and Brown P.D. (2009). An appraisal of ultramicrotomy, FIBSEM and cryogenic FIBSEM techniques for the sectioning of biological cells on titanium substrates for TEM investigation. Journal of Microscopy. 234(1), 16-25
- Fay M.W., Han Y., Brown P.D., Harrison I., Hilton K.P., Munday A., Wallis D., Balmer R.S., Uren M.J. and Martin T. (2008). Structural and electrical characterization of AuPtAlTi Ohmic contacts to AlGaN/GaN with varying annealing temperature and Al content. Journal of Applied Physics. 103(7), 074501
- Han Y., Fay M.W., Brown P.D., Novikov S.V., Edmonds K.W., Gallagher B.L., Campion R.P. and Foxon C.T. (2007). Microstructural characterization of low-temperature grown GaMnN on GaAs(001) substrates by plasma-assisted MBE Semiconductor. Science and Technology. 22(10), 1131-1139
- Fay M.W., Han Y., Brown P.D., Edmonds K.W., Wang K., Gallagher B.L., Campion R.P. and Foxon C.T. (2006). Characterization of Ga1-xMnxAs/(001)GaAs epilayers grown by low-temperature molecular beam epitaxy. Philosophical Magazine Letters. 86(6), 395-401