Both are used in Characterisation but which feature or property they are focused on?
HI Neha, these are some of the differences
• SEM is based on scattered electrons while TEM is based on transmitted electrons.
• SEM focuses on the sample’s surface and its composition whereas TEM provides the details about internal composition. Therefore TEM can show many characteristics of the sample, such as morphology, crystallization, stress or even magnetic domains. On the other hand, SEM shows only the morphology of samples.
• The sample in TEM has to be cut thinner whereas there is no such need with SEM sample.
• TEM has much higher resolution than SEM.
• SEM allows for large amount of sample to be analysed at a time whereas with TEM only small amount of sample can be analysed at a time.
• SEM is used for surfaces, powders, polished & etched microstructures, IC chips, chemical segregation whereas TEM is used for imaging of dislocations, tiny precipitates, grain boundaries and other defect structures in solids
• In TEM, pictures are shown on fluorescent screens whereas in SEM, picture is shown on monitor.
• SEM also provides a 3-dimensional image while TEM provides a 2-dimensional picture.
SEM (Scanning Electron Microscope) is used to characterized the surface morphology, particle size (Not able to measure nano size powders), EDS (a analysis tool of SEM) used for elemental analysis in your composition, its able to detect contamination in your composition, you can use it to view cross-sections of coatings deposit, microstructures, thickness and many more.
beside TEM is a high resolution tool (Transmission Electron Microscope) , able analyze at high resolution at nano level. TEM used to measure nano particles size, measurement of grain size, crystallite size, atomic arrangement in material, formation of new phases with very low amount which can not detect by XRD, by using TEM we can detect low amount (10 %
HI Neha, these are some of the differences
• SEM is based on scattered electrons while TEM is based on transmitted electrons.
• SEM focuses on the sample’s surface and its composition whereas TEM provides the details about internal composition. Therefore TEM can show many characteristics of the sample, such as morphology, crystallization, stress or even magnetic domains. On the other hand, SEM shows only the morphology of samples.
• The sample in TEM has to be cut thinner whereas there is no such need with SEM sample.
• TEM has much higher resolution than SEM.
• SEM allows for large amount of sample to be analysed at a time whereas with TEM only small amount of sample can be analysed at a time.
• SEM is used for surfaces, powders, polished & etched microstructures, IC chips, chemical segregation whereas TEM is used for imaging of dislocations, tiny precipitates, grain boundaries and other defect structures in solids
• In TEM, pictures are shown on fluorescent screens whereas in SEM, picture is shown on monitor.
• SEM also provides a 3-dimensional image while TEM provides a 2-dimensional picture.
Hi Neha,
The scale is different. SEM is typically not used at as high of magnifications as TEM. Also, with SEM you are looking at surfaces, and in backscatter mode you can observe compositional differences (and with EDS obtain chemical differences); and with TEM you can observe close to atomical structure as well as obtain crystallographic information.
SEM is mostly used for surface morphology of a material or a film layer that you ve modified or etc. With SEM you can see the 3D structure of your sample. According to your sample SEM may become a better way to visualize your sample. TEM is quitely useful for tiny samples (nanoparticles etc. ) and you can obtain 5 nm sample micrographs. And TEM presents you 2D structure of your sample.
SEM is mostly used for the surface characterization and the magnification mechanism is based on the electron from the sample. TEM is used to characterize very thin sample and the electron penetrates through the sample and magnifies onto imaging device
in SEM- back scattered electron. secondary electron, characteristic X-ray and chathodoluminescence produced after collision with the samples are used for the imaging of samples to get is surface morphology and 3D-impression. atomic scale imaging cant be done
in TEM- the transmitted electron from the samples are used to produce 2D image. atomic scale imaging can be done i.e. high resolution than SEM.
Both are involved common practizing in the surface, morphology, and phase nature. but TEM is more preferential than SEM due to thier inferior details about the particular plane of miller indices study, phase impurities, defects in crystalline solid materials, and extended magnification range features. Those bulk particles of SEM can be finely resoled as single particle in TEM analysis. Nano particles size determination is more reliable information in TEM characterisation rather than SEM study. Doped of any element within the lattice TEM exhibits the shifts where as SEM difficult to conformation. TEM information about dark and bright ring effect that we can able to predict the crystal defects but it is not in SEM analysis. However, SEM is sufficient informations on their surface magnification.
How TEM analysis can be carried out for fine particles? During TEM analysis high vacuum is created and particles may get absorbed due t vacuum.
For this case, the technicians are doing particle pre treatment for contamination free from adsorption (tedious sampling procedure). In TEM, the particle size is analysed by basic principle of electron beam scatter at particular atomic plane. Under high vacuum condition this electron beam can be free path move to optical detector. In addition there many mathematical projection softwares are available to determine the particle size view along three dimension way . I remembered that, SEM is also involved the secondary emission phenomenon for surface morphology study. In that bombardment of electron beam capture by using two focal lenses vertical and horizontal should be match at particular point on focusing plane. This point some times may mathematically miss matched at certain view of low angle, resulting we will getting blurring resolution in SEM analysis. TEM has solved this problem by clear cut edge principle of quantum wave function for individual particles in 3D. Even the single crystal is developed under homogeneous condition and i guess the absorption wont be interfered with electron scattered phenomenon.
SEM= Scanning electron microscope, an electron beam(~20kV) will scan the surface of the thick sample and signals that arise out of electron-beam specimen interaction are used for getting the desired information in your sample. ex: (i)secondary electron ( high resoution imaging of surface features, fractography); (ii) Back scatteered electrons - composition contrast image, Orientation imaging (iii) X-rays ( chemical composition, EDS, WDS )
TEM =Transmission electron microscope, high KV(~200kV) electron beam is passed through electron transparent thick sample and the signals that are collected below the sample used to understand the sample character. ex: (i) Bright field image and dark field imaging = microstructural features like grains, dislocations, precipitates etc., (ii) SADP =selected area diffraction (crystal structure information of your sample)
Better visit a nearby facility having SEM and TEM, rather than studying about it. serach for images/results obtained related to SEM and TEM.
Neha,
The difference is that both works with principle of electron diffraction/scattering but one is in reflection mode where as the other one is in Transmission mode (TEM).
Excellent summary of TEM & SEM! Thanks to all contributors! I'm still in the process of reviewing your comments. I'll add when I understand all points of view better.
Meanwhile here's some fodder for thought - Bragg XRD Microscopy! Nano structural information! Combines the benefits of AFM, SEM & TEM but with a lot of "room to improve" in the spatial resolution department (orders of magnitude). Other than this temporary disadvantage, here are several advantages of Bragg XRD Microscopy:
1. NDE - No (minimal?) sample preparation required. In situ!
2. Reflection & transmission modes possible. Many more!
3. Ambient environment OK! No vacuum needed. In situ!
4. Low tech!? (Don't need a PhD to operate).
5. Real Time.
6. Cost effective!
7. Sub-micron spatial resolution capabilities presently. Femtometer lattice strain resolution through reciprocal space. The spatial resolution limit would be about the wavelength of the X-rays used. The spatial resolution of the detectors presently is the challenge.
8. Perfectly suited for real time R&D and production environments.
9. Compact, safe, portable design feasible for "field" applications. (Fatigue, Security etc.)
10. You ought to check it out with an open mind! Think "out of the box"!
Live demos possible in India (Bengaluru) and US (NJ). Adapts to most existing XRD equipment including Panalytical, Bruker, Rigaku, Bede, Phillips, GE Diano and most other dinosaurs out there. Bring out the beauty in your beast!
Example YouTube Videos: http://www.youtube.com/watch?v=IU0m4yI7D-k&list=PL7032E2DAF1F3941F&index=1
Example of GaAs: https://www.researchgate.net/post/What_are_the_causes_for_ASYMMETRY_in_the_Bragg_X-ray_Rocking_Curve_Profile_RCP_for_a_symmetric_004_GaAs_reflection
Though TEM has better advanced applications more than surface morphological view , then why cant do mode changes in SEM in to transition mode (TEM) . The applications are not be the meaning for mode usage.
Certainly, every techniques have own specific importance.
Dr Bisoyi
The transmission electron microscope was the tool used to discover the mechanism of precipitation hardening in Al-Cu alloys. While XRD has been around beforehand, the mechanism of hardening of the Al-4%Cu alloy (observed as early as 1928) could not be understood, because the precipitates were not visible with any existing technique prior to 1948. Every method has its specific use. SEM is used to just see the surface and get an idea of the local composition in EDS mode. TEM gives you local crystallographic information that you would not get otherwise. TEM in electron diffraction mode was used to make the first observations of the five-fold symmetry in quasi-crystals, for which Daniel Shechtman received the Nobel Prize in Chemistry in 2011. Each tool has its particular use. SEM is mainly a high-resolution optical microscope really, and you get a real image of the surface. TEM, as others have indicated requires special sample preparation, but finally it is also a microscope. XRD gives crystallographic information, but the local visualization is in my view a very strong advantage of TEM (and its various off-springs).
I don't believe on microscopy as the results that leads are never good average rather scattering and diffraction all the time better averaging as I did many a time.
In SEM technique one can use a thick sample as the electrons are made to scan on the surface (on bulk and cross-section) but the magnification is limited. In TEM, the electrons pass through the specimen and the magnification can be higher. For the transmission of electrons, the specimen should be very thin.
if u see the name carefully, it says SCANNING and TRANSMISSION. answered by many is more or less reveals that SEM records only Surface morhphology , while TEM can probe in much more depth because of the difference in wavelength attained by electrons. Secondly TEM is based on the quantum mechanical phenomenon which gives better resolution.. and ofcourse much more information about the sample..
In my view the average structural parameters assigned with SEM & TEM are not the reality, what generally scientists thinks rather it is better to go for electron diffraction for better averaging when one is doing TEM.
Dear All,
Great knowledge and information by you all! based on this can i have a broader meaning (if i have to explain it to an undergraduate student) like, SEM and TEM have relation ship like X-ray and CT scan
More like, XRD (real+reciprocal space) and Radiography/CT (real space only).
Using XRD (X-ray diffraction) one can measure average crystallographic coherence in the subject VOXEL of real space through its reciprocal space. I believe, Dillip is referring to this aspect of the techniques. Meaning, measuring an average precise Nano structural parameter for an entire sampling area/volume non-destructively & in situ.
All these methods (STEM, TEM, SEM, AFM, PL, EPD) in conjunction are needed to finally realize the contribution only from the sample and help other scientists believe in NDE Bragg XRD Microscopy which essentially combines the benefits of both SEM & TEM (STEM) at room temperature without vacuum. The spatial resolution of XRD Microscopy is presently around 1-5um but could easily be enhanced to sub-micron and better.
http://www.flickr.com/photos/85210325@N04/10221987094/
There are many things can be attributed to the difference between AFM and SEM image,
For example, the relatively slow rate of scanning during AFM imaging often leads to thermal drift in the image, making the AFM less suited for measuring accurate distances between topographical features on the image. AFM images can also be affected by nonlinearity, hysteresis, and creep of the piezoelectric material.
http://en.wikipedia.org/wiki/Atomic_force_microscopy
SEM : It is used for surface characterization. It uses SE and BSE for imaging. SEM can be upgraded like EDS, FIB, OIM etc. SEM sample preparation is quite easy when compared to TEM. So SEM is used for surface imaging, chemical analysis, texture,etc
TEM: As the name indicates it transmit the electrons through the sample. It give the details of few nano level of sample. But TEM sample preparation is very difficult. The sample thickness itself in microns level. TEM is used to study dislocation, Stacking fault, 1D defects etc
So it depend on ur application , if ur working level is macro to micro level then go for SEM, If it is micro to nano then TEM.
Dr.Nehaji, though both are characterization techniques to visualise the physical structure of the materials, there are some marked differences. Though both use electrons as beam for illumination, in SEM, it scans on the surface and the reflected image will be recorded. In this the sample can be thick as the electrons do not penetrate through the material to be examined. However, the magnification is limited to upto ~one hundred thousand. But the resolution is high. But in TEM, as the electrons have to transmit through the substances, the sample thickness should be very thin to allow the electrons to pass through. Further, in the TEM, we can have higher magnification than SEM so that the images of nano structures can be seen in a high magnification. However, the resolution is very poor because of higher magnification and hence the interpretation of the results require some expertise. In TEM, specimen preparation is the crucial thing.
Congrats Neha! Excellent question with great numbers for stats! Huge audience!
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It would be great to put together a comparative chart with sample size, sample prep, spatial resolution, nanostructural resolution, dynamic range and data acquisition rate for SEM, TEM, AFM along with other pros and cons. Here is an attempt from the past with lots of information missing. I intend to include many of the salient points from this present discussion soon :-)
Something happened to the attachment. I'll repost soon.
Please refer the following too.
http://www.sciencedirect.com/science/article/pii/S0968432811001235
SEM images are 3-D & are accurate representations while TEM pictures are 2-D. When there is a choice in selection of TEM or SEM, the nature of the material and specimen preparation are a determinants. The thin film required for TEM generally requires an ultra-microtome and mounting on a grid support is difficult Where as there is no such need with SEM sample.SEM may require surface etching or freeze fracture, plus a conductive coating.
Hi,
Electron microscope follows the same ideas of optical microscope, but uses electrons instead of light;“Lens” here are not the optical materials (like glass), but electrical field.
A Scanning Electron Microscope uses a beam of electrons to scan the surface of an object to create an image detailing the topography and composition of the object’s surface.
A Transmission Electron Microscope is used to magnify objects. It aims a beam of electrons onto the object to form a magnified image called a micrograph.
In SEM an electron beam is focused into a small probe and is rastered across the surface of a specimen.Several interactions with the sample that result in the emission of electrons or photons occur as the electrons penetrate the surface.These emitted particles can be collected with the appropriate detector to yield valuable information about the material.The most immediate result of observation in the scanning electron microscope is that it displays the shape of the sample.The resolution is determined by beam diameter.
In transmission electron microscopy (TEM), a beam of highly focused electrons are directed toward a thinned sample (
Hai
Most of the features about SEM and TEM are described by all answers and it has given great information
SEM may be used for studying fracture surface of materials (failure analysis) also
All above answers have explained the differences however 3D TEM is possible.
SEM (Scanning Electron Microscopy) provides only the morphology (size and shape) whereas the TEM (Transmission Electron Microscopy) provides the additional informations like crystallinity, arrangement of the atoms (Fringe Width) too.
Using TEM one can also see the material adhered at the surface very clearly.
The resolution power of the SEM is lower than TEM. SEM can only be used to see the samples of size up to 10 nm but if the samples are smaller than 10 nm, then TEM becomes necessary.
BTW I believe there are other TEM techniques to measure Nano structural parameters like lattice strain below the "nm" range noted earlier. One such method would be the use of Kikuchi lines, yes?
https://en.wikipedia.org/wiki/Kikuchi_line
TEM requires extensive sample preparation. The thickness of the specimens to be examined under TEM should be less that 100nm. SEM's sample prep techniques are not that difficult comparatively. SEM is a better tool for surface characterization as compared to TEM which is better for internal structure analysis.
TEM is good for knowing crystallization and internal structure and size.
1.TEM shows nano level resolution .SEM shows micro level resolution. 2.Sample preparation is more difficult for TEM analysis than SEM analysis .3.• SEM focuses on the sample’s surface and its composition whereas TEM provides the details about internal composition like dislocation , twin , precipitates etc
TEM vs SEM
Both SEM (scanning electron microscope/microscopy) and TEM (transmission electron microscope/microscopy) refer both to the instrument and the method used in electron microscopy.
There are a variety of similarities between the two. Both are types of electron microscopes and give the possibility of seeing, studying, and examining small, subatomic particles or compositions of a sample. Both also use electrons (specifically, electron beams), the negative charge of an atom. Also, both samples in use are required to be “stained” or mixed with a particular element in order to produce images. Images produced from these instruments are highly magnified and have a high resolution.
However, an SEM and TEM also share some differences. The method used in SEM is based on scattered electrons while TEM is based on transmitted electrons. The scattered electrons in SEM are classified as backscattered or secondary electrons. However, there is no other classification of electrons in TEM.
The scattered electrons in SEM produced the image of the sample after the microscope collects and counts the scattered electrons. In TEM, electrons are directly pointed toward the sample. The electrons that pass through the sample are the parts that are illuminated in the image.
The focus of analysis is also different. SEM focuses on the sample’s surface and its composition. On the other hand, TEM seeks to see what is inside or beyond the surface. SEM also shows the sample bit by bit while TEM shows the sample as a whole. SEM also provides a three-dimensional image while TEM delivers a two-dimensional picture.
In terms of magnification and resolution, TEM has an advantage compared to SEM. TEM has up to a 50 million magnification level while SEM only offers 2 million as a maximum level of magnification. The resolution of TEM is 0.5 angstroms while SEM has 0.4 nanometers. However, SEM images have a better depth of field compared to TEM produced images.
Another point of difference is the sample thickness, “staining,” and preparations. The sample in TEM is cut thinner in contrast to a SEM sample. In addition, an SEM sample is “stained” by an element that captures the scattered electrons.
In SEM, the sample is prepared on specialized aluminium stubs and placed on the bottom of the chamber of the instrument. The image of the sample is projected onto the CRT or television-like screen.
On the other hand, TEM requires the sample to be prepared in a TEM grid and placed in the middle of the specialized chamber of the microscope. The image is produced by the microscope via fluorescent screens.
Another feature of SEM is that the area where the sample is placed can be rotated in different angles.
TEM was developed earlier than SEM. TEM was invented by Max Knoll and Ernst Ruska in 1931. Meanwhile, SEM was created in 1942. It was developed at a later time due to the complexity of the machine’s scanning process.
Summary:
1.Both SEM and TEM are two types of electron microscopes and are tools to view and examine small samples. Both instruments use electrons or electron beams. The images produced in both tools are highly magnified and offer high resolution.
2.How each microscope works is very different from another. SEM scans the surface of the sample by releasing electrons and making the electrons bounce or scatter upon impact. The machine collects the scattered electrons and produces an image. The image is visualized on a television-like screen. On the other hand, TEM processes the sample by directing an electron beam through the sample. The result is seen using a fluorescent screen.
3.Images are also a point of difference between two tools. SEM images are three-dimensional and are accurate representations while TEM pictures are two-dimensional and might require a little bit of interpretation. In terms of resolution and magnification, TEM gains more advantages compared to SEM.
Read more: http://www.differencebetween.net/science/difference-between-tem-and-sem/#ixzz4ofnZDOFV.
How we can measure any compound or sample by scanning electron microscope
The difference is already in the term: scanning (SEM) and transmission (TEM) electron microscopy. In first case, the resulting image based on reflected electrons, in the other case – the transmitted one. SEM also allows for elemental analysis (EDS-Energy-dispersive X-ray spectroscopy) as well as structural analysis (Electron backscatter diffraction (EBSD)). In most cases, a chemist or a material scientist does not need to know the details of the technique, but to understand what information he can get with it. I.e., electron microscopy gives not just an image, but also a lot of information about the composition and structure of the sample. For more information is much easy to read good tutorial.
In terms of magnification and resolution, TEM has an advantage compared to SEM. TEM has up to a 50 million magnification level while SEM only offers 2 million as a maximum level of magnification. The resolution of TEM is 0.5 angstroms while SEM has 0.4 nanometers. However, SEM images have a better depth of field compared to TEM produced images. Another point of difference is the sample thickness, “staining,” and preparations. The sample in TEM is cut thinner in contrast to a SEM sample. In addition, an SEM sample is “stained” by an element that captures the scattered electrons.
Sample preparation of SEM is more simple when compared to that of TEM. TEM has a much higher resolution in the range of 1nm or less when compared to SEM which falls in the range of 10 nm. SEM only shows the morphology of samples while TEM shows holography, morphology, crystallization.
One can also estimate thickness of the films using cross-sectional SEM view.
TEM penetrate into a sample than SEM and can image an object at very high precision .TEM has a high level of resolution in the range of 0.1-1nm when compared to SEM which meaures higher particles above 5nm . TEM requires transmission electron for imaging while SEM uses back scatter electrons for imaging .
TEM uses a broad static beam whilst SEM beam is focused to a fine point and scans line by line over the sample surface in a rectangular raster pattern.
https://www.fei.com/introduction-to-electron-microscopy/sem/
SEM is used for the surface morphology of the samples in form of powder, pellet or film. Working potential is 50 kV.
While TEM is used for knowing the internal structure of the samples.
Working potential is 200kV.
These are some of the differences
• SEM is based on scattered electrons while TEM is based on transmitted electrons.
• SEM focuses on the sample’s surface and its composition whereas TEM provides the details about internal composition. Therefore TEM can show many characteristics of the sample, such as morphology, crystallization, stress or even magnetic domains. On the other hand, SEM shows only the morphology of samples.
• The sample in TEM has to be cut thinner whereas there is no such need with SEM sample.
• TEM has much higher resolution than SEM.
• SEM allows for large amount of sample to be analysed at a time whereas with TEM only small amount of sample can be analysed at a time.
• SEM is used for surfaces, powders, polished & etched microstructures, IC chips, chemical segregation whereas TEM is used for imaging of dislocations, tiny precipitates, grain boundaries and other defect structures in solids
• In TEM, pictures are shown on fluorescent screens whereas in SEM, picture is shown on monitor.
• SEM also provides a 3-dimensional image while TEM provides a 2-dimensional picture.
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