FAQs of Scanning Electron Microscope testing (SEM Analysis)

What is SEM analysis?

SEM analysis refers to the process of using a Scanning Electron Microscope (SEM) to examine the surface morphology of a sample at high magnification. The SEM uses an electron beam to scan the surface of the sample, producing high-resolution images that can reveal details about the sample's surface structure and by attaching EDAX we can be identify the composition.

What are the applications of SEM testing?

SEM testing is used in a variety of fields, including Pharmaceuticals, Materials science, Engineering, Biology and electronics. It is often used to study the surface morphology of materials, to identify the composition of substances, and to analyze the microstructure of materials.

How does SEM work?

In SEM testing, the sample is placed in a vacuum chamber and bombarded with a beam of electrons. These electrons will interact with the atoms in the sample, producing secondary electrons, backscattered electrons and X-rays. The secondary electrons are detected by the detector. These interactions provide information about the sample's structure and composition, which is used to create high-resolution 2D images of the sample.

What are the advantages of SEM?

SEM offers several advantages, including high magnification and resolution, the ability to observe both conductive and non-conductive materials (Sputter coated to make it conductive), and the ability to analyze a wide range of samples, from large objects to small particles.

What is sputter coating in SEM analysis?

Sputter coating is a process used in Scanning Electron Microscopy (SEM) to prepare non-conductive samples for analysis. The process involves depositing a thin layer of a conductive material, such as gold or platinum, onto the surface of the sample to make it conductive.

The sputter coating process works by bombarding the surface of the sample with a beam of positively charged particles, known as ions, which are emitted from a sputter source. The ions dislodge atoms from the surface of the sample, and the conductive material is deposited onto the sample to form a thin, uniform layer.

Sputter coating is important in SEM analysis because it enables the examination of non-conductive samples, which would otherwise not be visible in the SEM. By making the sample conductive, the electrons emitted by the SEM can interact with the sample and produce a high-resolution image.

It is important to note that sputter coating can alter the surface of the sample and introduce artefacts into the image. Therefore, it is important to choose a sputter coating material that is compatible with the sample and to carefully control the conditions of the sputter coating process to minimize the risk of sample damage and artefacts.

What are the limitations of SEM?

Here are few limitations of Scanning Electron Microscopy (SEM):

1. Conductivity of sample: SEM requires that the sample being examined must be electro conductive or coated with a conductive material. This can limit the types of materials that can be analyzed using SEM.
2. Vacuum essential: SEM operates in a vacuum environment, which can limit the types of samples that can be examined and the conditions under which they can be examined. Wet (Moistened) samples cannot be used in SEM.
3. Sample preparation: SEM requires that samples be carefully prepared and mounted, which can be time-consuming and complex.
4. Sample damage: There is a risk of sample damage during the SEM imaging process, especially for delicate or sensitive samples.
5. Cost: SEM equipment and instrumentation can be expensive, and the process can be complex, requiring specialized knowledge and training.
6. Resolution: While SEM provides high-resolution images, it may not be as sensitive as other imaging techniques, such as transmission electron microscopy (Even a nano particles can be examined), in terms of detecting subtle differences in sample structure and composition.