Photocathode having ultra-thin protective layer

Abstract

A photocathode structure having a photoelectric face plate protective layer, in order to prevent a photoelectric effect from being deteriorated sharply due to a high reaction of oxygen with respect to most of existing photoelectric face plate materials when the photoelectric face plate used for generating photoelectrons by a photoelectric effect is exposed to the atmosphere, is provided. For example, a diamond-like carbon thin layer is used as a photocathode protective layer, to thereby perform a function of protection of the photoelectric face plate through isolation of the photoelectric face plate from the atmosphere and enable electrons generated from the photoelectric face plate to pass through a diamond-like carbon thin layer, which is deposited thinly, by the tunneling effect so that the performance of the photocathode is not affected. By using the protective layer, the processes subsequent to the photoelectric face plate deposition process can be freely performed in the atmosphere, to thereby simplify the whole process. As a result, a production cost is lowered, and manufacturing of a device or apparatus using a large-are photocathode is facilitated.