secondary-electron detector

A detector that is used for detecting secondary electrons emitted from the specimen surface by electron-beam illumination. The main elements of the detector are a scintillator and a photomultiplier tube (PMT). To efficiently collect low-energy secondary electrons (normally, several 10 eV), a positive potential (voltage) of about 10 kV is applied to the scintillator against the specimen. Accelerated secondary electrons are converted into visible light by the scintillator, and the light is guided to the PMT through a light pipe. Then, the light signal is converted into an electric signal and the electric signal is amplified. A secondary-electron image is obtained by displaying the intensity of the detected secondary electrons on a computer monitor screen as a series of bright spots synchronized with the scan of the electron probe.

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