FIELD EMISSION TYPE ELECTRON SOURCE

摘要

PROBLEM TO BE SOLVED: To provide a field emission type electron source where any excessive emission of electrons can be prevented. SOLUTION: In the device, a conductive layer 8 is formed on one surface of an insulating substrate 11, a high-field drift layer 6 provided with a drift part 6a consisting of an oxidized porous polycrystalline silicon layer on the conductive layer 8 and a separating part 6b consisting of a polycrystalline silicon layer formed on the periphery of the drift part 6a and a surface electrode 7 is formed on the high-field drift layer 6. An insulating film 16 constituted from silicon oxidized film is made to intervene between a part of the drift part 6a that is in the vicinity of the boundary with the separating part 6b and the surface electrode 7. A field alleviating means to make the field strength in the part near the boundary with the separating part 6b in the drift part 6a smaller than the field strength in the central part of the drift part 6a is constituted by the insulating film 16.