Scanning Electron Microscopy (SEM)
Zeiss Supra 55 VP
The Supra 55 VP is a high-resolution scanning electron microscope (SEM) from Zeiss. This electron microscope is a versatile instrument for characterizing the structure and composition of a wide variety of sample types. The four available imaging detectors (three secondary electron detectors and one backscattered electron detector) allow operation in high vacuum as well as low vacuum, which is useful if a sample is non-conductive and cannot be coated with a conductive material.
Furthermore, the instrument is equipped with three detectors from Oxford Instruments: one EDX, one WDX, and one EBSD detector are permanently integrated into the system.
Possible applications
- Images of a sample (secondary electrons, backscattered electrons)
- Images of non-conductive samples in low vacuum mode
- Qualitative and quantitative composition of a sample via its X-ray spectrum (spot, line, area)
- Phases, orientation, and grain boundaries of crystals in metals, ceramics, and minerals
- Electron beam lithography
- In-situ measurements at a temperature and under tensile load
Contact Person
Puchegger, Stephan
Head
Währinger Straße 38-42
1090
Wien
Room: 3342
Email
Copy email to clipboard
+43-1-4277-73802
Terms of use and usage fees
The Zeiss Supra 55 VP is not a self-service device. Please get in touch if you are interested in scheduling a measurement appointment. By using this service, you agree to the terms of use. In particular, the mandatory mention of the faculty center in the acknowledgments if measurement data is used in a publication.
You do not need to take any tests to use this device.
| User group | Hourly Rate | Cost per Sample |
|---|---|---|
| Faculties of Physics and Chemistry | - | - |
| Vienna Life Science Instruments | 25 € | 5 € |
| University users | 50 € | 5 € |
| Non-university users | 100 € | 5 € |
Sample stubs and conductive double-sided adhesive tape are provided to users. Samples can also be embedded in resin and polished if required. Other materials, such as silicon wafers, must be purchased by the users or their groups.
We also charge for the costs of our staff for training sessions and measurements that cannot be carried out independently.
| User group | Hourly Rate for the Operator | Note |
|---|---|---|
| Faculties of Physics and Chemistry | - | |
| Vienna Life Science Instruments | 70 € | 1. |
| University users | 70 € | 1. |
| Non-university users | 100 € |
- Under a publication agreement, the hourly rate for our employees is also waived.
Specifications
| Device Parameter | Value or Range |
|---|---|
| Cathode | Field Emission |
| Accelerating Voltage | 20 V – 30 kV |
| Sample Current | 4 pA – a few nA |
| Resolution | 1.0 nm @ 15 kV 1.7 nm @ 1 kV 3.5 nm @ 200 V 2.0 nm @ 30 kV (VP-Mode) |
| Magnification | 12–900.000× |
| VP-Vaccuum | 2–133 Pa, adjustable in 1-Pa increments |
| Detectors | Inlense Everhart–Thornley VPSE 4Q–BSD EDX WDX EBSD |
| Sample Chamber | 330 mm (Ø) × 270 mm (h) CCD-Kamera with IR illumination |
| Sample Stage | X = 130 mm Y = 130 mm X/Y-Positioning accuracy = 2 um Z = 50 mm T = −4 bis 70° R = 360° (continuously) |
| Micro-Positioning Table | X = 20 mm Y = 20 mm X/Y-Positioning accuracy = 100 nm |
| Peltier Table | Temperature range = −50 to 100°C |
| Tensile Test Machine | Deben MT200, Maximum Load 200N. 10mm Movement Range |
Downloads
Downloads are only visible to logged-in staff of the Chemistry and Physics departments. Click here to log in.
Are my samples suitable for electron microscopy?
In general, especially in electron microscopy, the type of sample has a major influence on the quality of the results.
Conductivity
In an electron microscope, the sample is continuously bombarded with an electron beam, which naturally also deposits energy in the sample and heats it locally. This results in several necessities:
- The samples must be suitable for vacuum analysis and therefore (largely) dry.
- The electrons must also be discharged, otherwise the sample will become charged.
- The sample must possess a certain degree of temperature stability, otherwise it will disintegrate under the electron beam.
The effects of electrostatic charging can range from a slight "wandering" of the image to the extreme case where the charge is so strong that the entire electron beam is reflected towards the top of the vacuum chamber, which is then visible in the image, Therefore, it is almost essential that a sample be conductive. Some samples, such as metals, are inherently conductive. If they are not, there are two possibilities:
- The samples can be coated with a thin layer of metal to make them sufficiently conductive. The advantage is that this layer reduces local heating of the sample and improves image contrast. The disadvantage is that a layer is applied to the sample, which, depending on the metal and its thickness, can also form its own, potentially interfering structures.
- If coating is not possible or desirable, as with archaeological samples, a suitably equipped electron microscope can be operated with a small amount of gas in the chamber to dissipate the charge. The disadvantage is that the images are typically noisier, and there are also some other limitations.
Sample carrier
Samples are typically introduced into the electron microscope in two ways:
- Mounted on sample carriers, which typically have a diameter of 12 mm. The sample or sample material must be attached to or mounted on these sample carriers.
- For powders, one option is to use double-sided conductive tape. Excess material must be blown off to prevent individual particles from being drawn into the column.
- A solution containing particles can be drop-loaded onto a suitably doped small piece of silicon wafer, which is then attached to the sample holder with tape. (These wafer pieces typically range in size from 3 mm x 3 mm to 1 cm x 1 cm and can be ordered from electron microscopy suppliers.) This has the advantage that the support surface is very smooth, allowing the particles to be easily identified after the solution has dried. Furthermore, the conductivity of such wafers is significantly better than that of conductive tape, minimizing potential electrostatic charging. Another very good option is to use TEM grids, which are then attached at the edges with tape. With these, excess material can be easily removed with a cloth placed underneath the sample during application.
- Embedded in conductive resin, typically when the sample needs to be ground. There are two methods: cold embedding and hot embedding. In cold embedding, the sample is heated to approximately 95 °C, while in hot embedding, it is heated to approximately 180 °C. Hot embedding is preferable whenever possible because the embedding material is more homogeneous and electrostatic charging is virtually eliminated. Non-conductive resins, often used for samples in optical microscopy, are poorly suited. These would require post-processing, such as vapor deposition or coating the resin with silver lacquer.
Sample quantity and size
Electron microscopes are typically used where high magnification is required. This also means that the area under observation is often very small. This, in turn, means that not much sample material is needed. Especially with powders, large clumps are often a disadvantage, because it contributes to the problem of electrostatic charging. When working with particles in solutions, it is recommended to perform a dilution series on several sample carriers during the initial experiments to find the dilution at which no particle aggregations or even entire layers of particles form, which also promote electrostatic charging. Less is more in this case.