Source: Laboratory of Dr. Andrew J. Steckl — University of Cincinnati

A scanning electron microscope, or SEM, is a powerful microscope that uses electrons to form an image. It allows for imaging of conductive samples at magnifications that cannot be achieved using traditional microscopes. Modern light microscopes can achieve a magnification of ~1,000X, while typical SEM can reach magnifications of more than 30,000X. Because the SEM doesn’t use light to create images, the resulting pictures it forms are in black and white. 

Conductive samples are loaded onto the SEM’s sample stage. Once the sample chamber reaches vacuum, the user will proceed to align the electron gun in the system to the proper location. The electron gun shoots out a beam of high-energy electrons, which travel through a combination of lenses and apertures and eventually hit the sample. As the electron gun continues to shoot electrons at a precise position on the sample, secondary electrons will bounce off of the sample. These secondary electrons are identified by the detector. The signal found from the secondary electrons is amplified and sent to the monitor, creating a 3D image. This video will demonstrate SEM sample preparation, operation, and imaging capabilities.

1. Preparation of the Sample

1. Place sample onto sample stub. If necessary, carbon tape may be used to adhesively bond the sample to the stub.
2. Place the sample into a gold sputtering system. Using a mini-gold sputter, sputter gold for 30 s at ~ 70 mTorr pressure. A different gold layer thickness may be necessary depending on the geometry of the sample. More rough or porous surface requires a longer sputtering time.
3. Remove stub from gold sputtering system.

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