Publisher Summary This chapter provides an overview of negative-electron-affinity (n.e.a.)- secondary emitters and cold cathodes. Both of these devices, when their potential is fully explored, may prove to be at least as significant for imaging devices as the n.e.a. photocathodes. In case of n.e.a. cold cathode, the electrons are excited into the p-type layer by the junction at the left. In a Si p–n-junction cold cathode, bias is applied by contacting the n-type wafer and the polycrystalline p-type layer. The polycrystalline layer makes contact with the single crystal that has grown epitaxially in the hole. The current is injected into the p-region where there is no contact covering the surface. It is felt that this n.e.a. cold cathode will significantly affect pick-up tube techniques because of the higher current density and lower velocity spread that it makes available. The device parameters that have been designed around the available beam characteristics may be relaxed, leading to devices with greatly improved performance. Further, the lack of emitted light and very low power requirements increase the utility of this type of cathode. It seems that this structure is very close to an ideal limit for an electron beam source.

B.F. Williams

R.U. Martinelli

Negative Electron Affinity Secondary Emitters and Cold Cathodest

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