Detailed Introduction to the Principles and Applications of Scanning Electron Microscopy

scanning electron microscope（Scanning Electron Microscope, SEM）It is a powerful microscope widely used in fields such as materials science, biology, and nanotechnology. The following is a detailed introduction to its principles and applications.

principle

1. Electron beam generation:

   - SEMUse an electron gun (usually a tungsten wire or field emission electron gun) to generate high-energy electron beams. The electron beam is accelerated to energy of several thousand to tens of thousands of electron volts by an accelerating voltage.

2. Electron beam scanning:

   - The electron beam is focused into small light spots through a focusing lens system and scanned on the surface of the sample. Scanning is controlled by an electromagnetic field to move the electron beam line by line on the surface of the sample.

3. Interaction with the sample:

   - When an electron beam collides with a sample, various signals are generated, including:

     - Secondary electronics: mainly used for imaging, providing morphological information of the sample surface.

     - Backscattered electrons: provide information on the composition and structure of the sample.

     - featuresXRadiation: used for chemical composition analysis.

4. Signal detection:

   - The generated secondary electrons and backscattered electrons are collected by the detector and converted into electrical signals. After amplification and processing, the electrical signal generates an image.

5. Image display:

   - Finally, the processed signal is used to form a high-resolution image of the sample on a display, displaying the surface features and microstructure of the sample.

application

1. Materials Science:

   - Used for observing the microstructure and defect analysis of materials such as metals, ceramics, polymers, etc.

2. biology:

   - Used for observing the morphology of cells, tissues, and biological samples, especially for observing cell surface features at ultra-high resolution.

3. Nanotechnology:

   - In the research of nanomaterials,SEMCapable of providing nanoscale imaging to assist researchers in analyzing nanoparticles and nanostructures.

4. Semiconductor industry:

   - Used for manufacturing and fault analysis of semiconductor devices, observing the microstructure of integrated circuits.

5. Geology:

   - Used for analyzing the composition, structure, and composition of ores, rocks, and other geological samples.

6. Fault analysis:

   - In the failure analysis of electronic components and materials,SEMCan be used to identify failure modes and causes.

7. Surface analysis:

   - Used to study the roughness, coating, and corrosion of material surfaces.

Advantages and limitations

- Advantages:

  - High resolution: capable of achieving nanometer level resolution.

  - Deep Depth of Field: Provides a larger depth of field, making the surface morphology of the sample clearer.

  - Multiple information acquisition: can simultaneously obtain information such as morphology, composition, and crystal structure.

- Limitations:

  - Sample preparation: The sample needs to be conductive and usually requires metal coating treatment.

  - Vacuum environment: It needs to be carried out under vacuum conditions, which limits the observation of certain samples (such as biological samples).

  - High cost: Equipment and maintenance costs are relatively high.

conclusion

Scanning electron microscope is a powerful tool widely used in multiple fields. Its high resolution and diverse information acquisition capabilities make it an important tool for microscopic analysis and research.