| Conventional photoelectric cathode materials are generally alkali metals?alloys?and III-V semiconductors with negative electron affinity.Their main feature is the high quantum efficiency.But the disadvantage is the strict using environment requirements.Compared with traditional photoelectric cathode materials,one-dimensional nanomaterials carbon nanotube have certain advantages in terms of stability,preparation and storage cost,and service life.However,the quantum efficiency of carbon nanotube cathode is low,and the superior performance of the carbon nanotubes is still not completely released.This paper proposed patterned carbon nanotube arrays to fully enhance the edge effect.And then the surface of carbon nanotubes were modified by gold nanoparticles with the help of the metal plasmon resonance effect.It enhances light absorption and localized electric field.The main research contents and results of this paper were as follows:?1?20?m×20?m square arrayed carbon nanotubes were prepared by UV lithography and chemical vapor deposition.And a high vacuum photoelectric testing platform was built.Under irradiation of 800 nm femtosecond pulsed laser,the quantum efficiency of carbon nanotube cathode improved from 1.23×10-5 to 4.51×10-5 after patterning.We analyzed its photoelectric emission mechanism as photoinduced field emission.And carbon nanotube array cathodes with different duty cycles were prepared.The tests also showed that the patterning can improve the photoelectric emission performance of the carbon nanotube cathode.?2?Different sizes of gold nanoparticles were prepared by thermal evaporation and thermal annealing.The absorption spectra of gold nanoparticles of different sizes were tested.The test results showed that the prepared gold nanoparticles have the localized plasmon effect.Then the carbon nanotubes modified by gold nanoparticle were prepared by the same process.Under irradiation of 800 nm femtosecond pulsed laser,the quantum efficiency of carbon nanotube cathode improved from 3.69×10-6 to 5.31×10-6 after modification by gold nanoparticles.The photoelectric emission mechanism was analyzed for multiphoton absorption when the optical power is low.And the photoelectric emission mechanism was analyzed for photoinduced field emission when the optical power is high.Finally,carbon nanotube cathodes modified by different sizes of gold nanoparticles were prepared.Photoelectric test results showed that the modification by gold nanoparticles can improve the photoelectric emission performance of the carbon nanotube cathode. |
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