Stabilization of a diamond cold cathode and its application to ultra high sensitive photodetector

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Throughout our research we have established a. model to explain the mechanism of the electron emission from heavily nitrogen doped CVD diamonds. We have investigated on the electron emission from not only polycrystalline samples, but also homo- and hetero-epitaxial samples. By a) assessing the electric field applied onto the vacuum by measuring-the emission current when variating the distance between the anode and the cathode, and b) from the results of RHEED, Hall measurement, REELS, and Raman Spectroscopy, we have proved the adequacy of our model. Within the last period, we have compared the emission properties of surface treated and non-surface treated diamond samples.Towards our final goal of obtaining an ultra high sensitive photodetector, we have used our diamond emitter as a cold cathode and a photoconductive amorphous selenium (a-Se) as the target. As a prototype, we have fabricated a diode and triode structured photodeter and succeeded in operating this device under voltage and vacuum lower than any know conventional photodetectors. The a-Se, however experienced crysallization after hours of operation, which decreased the performance, although, a small amount of arsenic doped into the selenium film was found to prevent this phenomena.