| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1996: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1995: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Since the proposition of this type electron emitter we have investigated sulfides, oxides and organic films as the electron acceleration layr. In the course it was noticed that the oxide layrs show some different behavior from those of other material. This research aimed to elucidate this peculiar characteristic of oxide electron emitter.
In the first year (1995), it was tried to obtain a high resistive thin film of ZnO for the use as an acceleration layr. A new technique was devised for the growth of oxide films, resulting an improved growth rate of ZnO thin films with setting proper intermissions during the reactive dc-sputtering.
In the second year (1997), the electronic properties of the thin films of TA_2O_5 and SiO_2 grown by the RF-sputtering method. Y_2O_3 and Al_2O_3 grown by electron-beam evaporation, and of above mentioned ZnO were evaluated to use for the electron-acceleration and electron-blocking layrs of the thin-film electron emitter. Then the divices with the composition ; Au-outlet electrode/SiO_2-acceleration layr/Ta_2O_5-blocking layr/Al-electrode, and also those with ZnS- and ZnO-acceleration layrs were fabricated and compared each other with their characteristics of electron emission.
The SiO_2-devices show the closer emission characteristic to the sulfide-devices compared with other oxide-devices, giving a distinct threshold voltage for electron emission by avalanche break-down. This result indicate that the electron emission due to avalanche break-down of the acceleration layr is more dominant in the SiO_2-acceleration layr under a high voltage owing to its better film quality than other oxide layrs. Much improved emission characteristics will be obtained, therefore, by excluding the absorption current caused by crystal defects and impurities.
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