Scanning electron microscopy (SEM) is commonly used as a material characterization technique. A focused beam of electrons is swept over the surface of a specimen in a raster pattern and any of several resulting emissions from the sample like secondary electrons, back scattered electrons or X-rays is detected. An image is then formed on a cathode ray screen by mapping the intensity of the detected signal as a function of the position of the incident beam. 

Main Use: High magnification imaging and composition (elemental) mapping.

Destructive: No, some electron beam damage

Magnification Range: 10´ -300,000´; 5000´-100,000´ is the typical operating range

Beam Energy Range: 500 eV to 50 eV; typically, 20-30 keV

Sample Requirements: Minimal, occasionally must be coated with a conducting film; must be vacuum compatible 

Sample Size: Less than 0.1mm, upto 10cm or more

Depth sampled: Varies from a few nm to a few µm, depending upon the accelerating voltage and the mode of analysis

Lateral Resolution: 1-50 nm in secondary electron mode

Bonding Information: No

Depth Profiling Capabilities: Only indirect

Instrument Cost: $100,000 - $300,000 is typical

Size: Electronics console 3ft ´ 5ft; Electron beam column  3ft ´ 3ft