Coatings for SEM and STM

Scanning electron microscope and STM samples are generally coated to provide an electrically conductive layer, to suppress surface charges, to minimize radiation damage, and to increase electron emission. The coating is intended to be a thin, continuous in situ replica of the specimen surface. The thickness and texture of the 

The saddle field ion gun was first used for traditional ion thinning of materials, such as metals [460]. The ion beam sputtering (IBS) method uses a fine, collimated, and water cooled ion source that sputters metal from a target onto the specimen surface. Argon is directed into the ion gun, and the specimen is neither heated nor bombarded by the plasma as is generally the case in ordinary sputter coating. The device is 

It is appropriate to discuss the potential imaging effects, or artifacts, in specimen preparation. For this discussion, the term artifacts will be reserved for those textures that are an effect of the preparation method and are incorrectly attributed to the specimen. The polymer micros-copist has to deal with such preparation effects daily and, thus, should be fully aware of both the causes and the appearance of the resulting structures. How can the microscopist know when the structures observed are an adverse preparation effect or a real structure of the material Experience is the best teacher, but there are some effects of metal coating, charging, and beam damage that are generally known to result in artifacts with polymer materials. 

If the area in the center of the image is bright, there is negative charging and the beam energy, 2. 

A study of various coating devices was conducted several years ago to identify the best conductive coating for high resolution SET taken using a TEM (with a scanning attachment) with a 

A mid-1980s dedicated SEM, with 4 nm resolution, was found to resolve even thin platinum 

In summary, compromises must be made in the choice of conductive coating techniques, depending on resolution. Issues to consider are capital cost, coating deposition time, ease of use and the resolution required for observation. 

Joy [335-338] has provided careful experimental studies of the effect of imaging at low voltages 

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