The Unit has two scanning electron microscopes available for staff and student use: The FEI NovaNano SEM and the Tescan MIRA3 RISE SEM. The instruments can be booked in advance for as long as is required for a particular experiment subject to user demand at that particular time. The Unit offers training in the operation of these instruments.
Please contact Miranda Waldron for any queries regarding our scanning electron microscopes: (021) 650 2818, or miranda.waldron@uct.ac.za.
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Tescan MIRA SEM
The Tescan MIRA SEM is a high resolution Field Emission SEM, with low kV imaging, low vacuum performance, Electron Beam Lithography, EBSD and Raman spectroscopy. The SEM was installed in 2017, was in operation by early 2018.
Summary of features:
- Secondary Electron Detector
- Retractable Backscatter detector
- In-Beam BSE detector
- Oxford EBSD detector
- Beam Deceleration Mode
- Decontaminator ( XEI)
- Variable Pressure mode
- E-Beam Lithography
- Beam Blanker,
- Drawbeam Advanced and Drawbeam Offline software
- WITEC RAMAN
- Motorized WITec Confocal Raman Imaging Extension for SEM,
- The Confocal Raman Imaging Extension includes:
- • WITec Confocal Raman Microscope base for SEM systems
- • Motorized WITec multi wavelength laser
- • Motorized and software controlled spectral calibration unit
- Adaptor for coupling to MIRA SEM
Details:
- High resolution in-lens secondary and backscatter detectors: These detectors sits inside the electron column and are used to produce high resolution images on a range of samples.
- Variable pressure mode: The MIRA SEM has a low vacuum backscatter detector which can be used in variable pressure mode to produce high resolution images on charging and uncoated samples. Beam distortions caused by sample charging can be minimized by introducing a gas or vapour into the sample chamber, primary electrons and electrons ejected from the sample are amplified in a gas ionization cascade produced by placing a positively charged electrode above the sample (Toth et. al. 2003. Ultramicroscopy v94(2):71-87). In the case of the MIRA SEM, distilled water is introduced into the chamber to produce improved images of charging samples, the amount of water and the chamber pressure can be modified according to the extent of the sample charging.
- Retractable backscatter detector: Retractable annular backscattered electron detector scintillator type (YAG crystal) with high sensitivity. This detector can be used to produce images based on sample density, but when used with a low beam voltage, the resulting images are topographic and resemble images taken with the secondary detector.
- EBSD detector: The Mira SEM has an Oxford EBSD system with Aztec HKL software, used to perform quantitative microstructure analysis on the nanometer scale.
- E-Beam Lithography: The system offers a range of lithographic products that enable a range of multidisciplinary research projects. It makes use of the latest hardware and control software that is integrated into the SEM and can produce features as small as 40nm, thus allowing lithographic techniques at the nanometre-scale. Applications include isolating single nanowires, nano-particles, nano-dots, nano-gates.
- Raman Integrated Scanning Electron Microscopy: The Mira SEM has the capability of doing correlative confocal Raman microscopy and Field Emission Scanning Electron Microscopy on the same platform. For more detail follow this link.
Training:
Should you need training please inquire at the Unit about the scheduling of individual training, carried out by Miranda Waldron (the EM Officer responsible for SEM applications). Training consists of an initial session where you are familiarised with basic Electron Microscopy and the software on the SEM. At the next session, you will undergo hands-on training under supervision, using your own samples. This will continue until you are competent and able to be left alone. Regular user charges will be charged whilst you are learning to use the SEM.
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Nova NanoSEM
The Nova NanoSEM is a high resolution Field Emission SEM, combining low kV imaging and analytical capabilities with unique low vacuum performance. The SEM was installed in March 2010, was in operation by April 2010 and is mainly used by staff and students from UCT, CPUT and UWC.
Summary of features:
- Field Emission Gun (FEG) high resolution SEM.
- Everhardt-Thornley SED
- In-lens SE detector (TLD-SE)
- In-lens BSE detector (TLD-BSE)
- Oxford EDX system including X-ray mapping with INCA data acquisition software,
- Nordlys Oxford EBSD detector with Flamenco data acquisition software,
- STEM BF DF HAADF detector,
- UHR Low vacuum Secondary detector
- UHR low vacuum Backscatter detector
- IR-CCD
- Nanoparticle X-ray mapping using STEM detector.
- Resolution @ optimum WD (High vacuum)
- 1.0 nm @ 15 kV (TLD-SE)
- 1.6 nm @ 1 kV (TLD-SE)
- 0.8 nm at 30 kV (STEM)
- Resolution @ optimum WD (Low vacuum)
- 1.5 nm @ 10 kV
- 1.8 nm @ 3 kV
Details:
- High resolution in-lens secondary detector: This detector sits inside the electron column and is used in conjunction with the immersion lens to produce high resolution images. The detector can be used in both secondary and backscatter modes on a range of samples.
- Beam Deceleration mode: This mode is used when imaging beam sensitive samples when a low kV is required.
- Low vacuum mode: The NanoSEM has a low vacuum backscatter detector and a low vacuum secondary detector. Either of these can be used in low vacuum mode to produce high resolution images on charging samples. Beam distortions caused by sample charging can be minimized by introducing a gas or vapour into the sample chamber, primary electrons and electrons ejected from the sample are amplified in a gas ionization cascade produced by placing a positively charged electrode above the sample (Toth et. al. 2003. Ultramicroscopy v94(2):71-87). In the case of the Nova NanoSEM, distilled water is introduced into the chamber to produce improved images of charging samples, the amount of water and the chamber pressure can be modified according to the extent of the sample charging.
- Low voltage backscatter detector: This detector can be used to produce images based on sample density and is very effective when imaging alloys. When used with a low beam voltage in combination with beam deceleration, the resulting images are topographic and resemble images taken with the secondary detector. Very useful for charging samples.
- STEM Detector: The STEM detector can be used on TEM samples that are either beam sensitive or have low contrast, such as biological specimens. In order to increase the contrast, various stains can be used on biological samples, but there is some risk of introducing artifacts during staining. STEM is a low dose technique compared with TEM so high resolution images can be produced using low kVs. Images are produced from electrons that have passed through the thin sample. Different types of signals can be produced by different beam scattering angles, these can be displayed simultaneously or individually, depending on the image required.
- EDS Detector: The NanoSEM has an Oxford X-Max silicon drift EDS detector which produces high resolution EDS spectra with productive count rates at low beam currents.
- EBSD detector: The NanoSem has an Oxford EBSD system, used to perform quantitative microstructure analysis on the nanometer scale.
Training
Should you need training please inquire at the Unit about the scheduling of individual training, carried out by Miranda Waldron (the EM Officer responsible for SEM applications). Training consists of an initial session where you are familiarised with basic Electron Microscopy and the software on the SEM. At the next session, you will undergo hands-on training under supervision, using your own samples. This will continue until you are competent and able to be left alone. Regular user charges will be charged whilst you are learning to use the SEM.
You can also browse through our online lectures for the EM for Biologists training course, which covers LM, SEM, TEM and Image Analysis.
Some SEM images
