Schottky field emission gun

Freshly fractured surfaces were examined by SEM in a LEO 1530 microscope with a Schottky field-emission gun without evaporating conductive layers prior to the investigation. EDX WDX... 

Similarly, the field emitter can be adapted by reducing the work function. The practical device is called the Schottky field emission gun, but it is really a field-enhanced thermionic emitter. The sharp tip is coated with zirconium oxide. The field is reduced by flattening the tip and acts to reduce the potential barrier, but the electrons are thermally excited over the low barrier, not sucked through it. 

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