| 摘要 |
The invention provides an electron beam device 1 comprising at least one field emission cathode 3 and at least one extracting electrode 5 , whereby the field emission cathode 5 comprises a p-type semiconductor region 7 connected to an emitter tip 9 made of a semiconductor material, an n-type semiconductor region 11 forming a pn-diode junction 13 with the p-type semiconductor region 7 a first electric contact 15 on the p-type semiconductor region 7 and a second electric contact 17 on the n-type semiconductor region 11. The p-type semiconductor region 7 prevents the flux of free electrons to the emitter unless electrons are injected into the p-type semiconductor region 7 by the pn-diode junction 13. This way, the field emission cathode 3 can generate an electron beam where the electron beam current is controlled by the forward biasing second voltage V 2 across the pn-diode junction. Such electron beam current has an improved current value stability. In addition the electron beam current does not have to be stabilized anymore by adjusting, the voltage between emitter tip 9 and extracting electrode 5 which would interfere with the electric field of electron beam optics. The present invention further provides the field emission cathode as described above and an array of field emission cathodes. The invention further provides a method to generate at least one electron beam.
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