Nanocarbon material (Ugleron and Astralens) is used for the first time for the production of metal porous cathode (MPC). It can be assumed that its implementation in the MPC matrix can change the mechanism and rate of occurrence of three-phase reactions of formation of active elements and oxygen and, thereby, improve its emission properties. The new technology of manufacturing MPC is aimed at solving the problem of increasing the durability of electro vacuum devices - more than 100,000 hours. The obtained results are intended for use in technologies for manufacturing of electron sources for electro vacuum devices used in space communication and navigation systems. In addition, they can be useful for other areas of electronics that use a metal-porous thermal cathode as sources of electron emission.
There are manufactured models with the use of Ugleron and Astralens in a sponge and emission substance. A layout using Ugleron in the emission substance is tested for durability and currently has an operating time of 40,000 hours. A model with the use of Astralens and Ugleron in a sponge and emission substance respectively is tested for maximum current density. To date, it shows results comparable to the standard cathode. However, there is a suggestion that cathodes with Astralens and Ugleron have a lower evaporation rate of the active substance. There is predicted longer durability than for the standard cathode at the same emissivity.
Crystallization of amorphous hydrogenated silicon thin films with femtosecond laser pulses is a currently developable technique for nanocrystalline silicon production for optoelectronics applications. The significant drawback of this technology is the hydrogen losses upon laser treatment of the film, while certain hydrogen concentration is essential to obtain high-quality material. Therefore we aimed to study the effect of post-hydrogenation of laser-modified amorphous silicon films on their hydrogen content and photoelectric properties. Using laser pulses of different fluence we obtained two-phase films with different crystalline volume fraction up to 60%. Post-hydrogenation procedure was found to partially compensate hydrogen out-diffusion and remarkably increase photoconductivity of highly crystallized films. At the same time the contribution of nanocrystalline phase to the total films' photoconductivity substantially increases. The results points out the effectiveness of applied hydrogenation procedure for a production of laser crystallized amorphous silicon films with suitable properties for optoelectronics.
Andrey Emelyanov, Mark Khenkin, Andrey Kazanskii, Pavel Forsh, Pavel Kashkarov, Evgeny Lyubin, Andrey Khomich, Mindaugas Gecevicius, Martynas Beresna, Peter Kazansky
This paper studies the effect of femtosecond laser treatment in air of hydrogenated amorphous silicon thin films (a-Si:H)
on their structural, electrical and photoelectric properties. The possibility of laser-induced crystallization of a-Si:H films
with controlled crystalline volume fraction was shown. A sufficient increase of dark conductivity was observed for laser
treated a-Si:H films which crystallinity exceeds 7%. Such increase was attributed to change in conductivity mechanism.
However, spectral dependences of absorption coefficient did not show any qualitative changes with the laser fluence
increase. It was found that spallation and oxidation of the film took place when laser fluence became reasonably high.
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